Zootaxa,Studies on the Canacidae (Diptera), subf ...

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Zootaxa 1692: 26–42 (2008) www.mapress.com / zootaxa/

ISSN 1175-5326 (print edition)

Copyright © 2008 · Magnolia Press

ISSN 1175-5334 (online edition)

ZOOTAXA

Studies on the Canacidae (Diptera), subfamily Apetaeninae. II. A review of the world subgenera of Apetaenus Eaton, with a special reference to the Australian and New Zealand species LORENZO MUNARI Co-operating Entomologist, Natural History Museum, S. Croce 1730, I-30135 Venezia, Italy. E-mail: [email protected]

Abstract A review of the world subgenera of Apetaenus Eaton is proposed, giving, contextually, a particular emphasis to the species from the Australian and New Zealand subantarctic archipelagos. The taxonomic status of Apetaenus watsoni Hardy is changed to A. litoralis watsoni Hardy n. stat. In this connection, Apetaenus litoralis Eaton is subdivided into three subspecies, of which A. litoralis marionensis n. ssp. from Marion Island (Kerguelen Biogeographical Province) is herein described. Furthermore, the genus Apetaenus is subdivided into three subgenera, namely Apetaenus s. str. Eaton, Listriomastax Enderlein, and Macrocanace Tonnoir & Malloch. A key to subgenera is proposed. With this second contribution the subfamily Apetaeninae has been reviewed worldwide, except for the subantarctic territories of South America, including the southernmost archipelagos, from which no species have hitherto been reported in the literature. Finally, some hypotheses on the evolution and dispersal of these flies around Antarctica are also proposed. Key words: Canacidae, Apetaeninae, Australia, New Zealand, subgenera of Apetaenus, subspecies of Apetaenus litoralis Eaton, new subspecies

Introduction Apetaeninae is a monotypic subfamily of Canacidae (D. K. McAlpine, 2007) including the only genus Apetaenus Eaton. These flies are endemic in the cold, sometimes cool-temperate, rocky seashores of the subantarctic islands (figs. 13, 15). Like the Coelopidae (kelp flies) they share the same kind of habitat which is often typified by the presence of thick heaps of brown algae regularly washed up by the waves on the rocky, intertidal zone. However, these flies also occur in the supralittoral zone, among tussock grasses or more or less strictly associated with penguin colonies and other sea birds (fig. 14). It is likely that Apetaenus species have an opportunistic, polysaprophagous diet in addition to a microalgal pabulum, which constitutes the main food resource (Séguy, 1940; Munari, 2007). The Apetaeninae are, therefore, flies which typically occur in remote, isolated, oceanic places influenced by severe, sometimes extreme living conditions for most organisms occurring there. The main target of this second contribution is to investigate more thoroughly the taxonomy of the Apetaeninae, including some new taxonomic proposals as well as the subdivision of the species Apetaenus litoralis Eaton into three subspecies, with description of a new subspecific taxon from Marion Island. Materials and methods Most specimens are double mounted, mostly glued or even micropinned to a card slip. Their study and illustration required the use of dissecting and compound microscopes, the latter used in particular for perusal of the genitalic structures. Micropincers and dissecting needles with lanceolate point were used to remove abdomens, which were macerated in a boiling, potassium hydroxide solution. The abdomens, once cleared in

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a hydrogen peroxide solution, were dipped in a 20% acetic acid solution for about one minute to fully neutralize the action of the caustic potash, and then rinsed in distilled water. Genitalia or the entire abdomen were then transferred to glycerine for observation. When necessary for a proper orientation, the anatomical piece was transferred from glycerine to glycerine jelly. The glycerine jelly was heated, and the piece appropriately oriented. After cooling, the embedded piece in glycerine jelly became immobilized. Abdomens and genitalia were in this way studied, photographed or drawn, and finally placed in a plastic microvial filled with glycerine, and immediately pinned below the specimen from which the anatomical piece was removed. Wings (figs. 7–10) were mounted in polyvinyl lactophenol and photographed by a digital camera applied to the dissecting microscope. The images obtained were then processed by means of a specific software (Corel Photo-Paint®). The descriptive terminology chiefly follows that of the Manual of Nearctic Diptera (J. F. McAlpine, 1981) and the Contributions to a Manual of Palaearctic Diptera (Merz & Haenni, 2000), except for the first antennal flagellomere, for which the term “postpedicel” (sensu Stuckenberg, 1999) has been used. In the text, the species as well as the collecting localities under each species are listed in alphabetical order. Holotype label data are quoted verbatim, i.e. without interpretation; a slash (/) indicates the end of a line of print or handwriting, two slashes (//) indicate the end of a label and the beginning of another. Significant supplementary or qualifying information is given in square brackets. The description of the new subspecies is based primarily on its holotype, but for a few characters also on the examination of the entire paratypical series. Abbreviations and acronyms of museums and other scientific institutions quoted in the text: HT AMNZ ANIC CMNZ LUNZ MCNV MNHN NMSA NZAC

Holotype. Auckland Institute and Museum, Auckland, New Zealand. Australian National Insect Collection, CSIRO Entomology, Canberra, Australia. Canterbury Museum, Christchurch, New Zealand. Entomology Research Museum, Lincoln University, Canterbury, New Zealand. Museo di Storia Naturale, Venezia, Italy (author’s collection). Muséum National d’Histoire Naturelle, Paris, France. Natal Museum, Pietermaritzburg, South Africa. New Zealand Arthropod Collection, Auckland, New Zealand.

A historical review The first citation of these flies from the Australian and New Zealand subantarctic islands dates to 1902, when Hutton described in the same paper both Ochtiphila australis (= Apetaenus australis) and Milichia littorea (= Apetaenus littoreus) from Campbell Island and Antipodes Islands, respectively. Tonnoir & Malloch (1926) transferred Hutton’s species to the new genus Macrocanace (type species: Milichia littorea Hutton, by original designation), which they described to include these two species. Subsequently, Womersley (1937) recorded Apetaenus litoralis Eaton, a species known at that time only from the French subantarctic islands, also from the remote, easternmost island of Macquarie. However, Hardy (1962) regarded Womersley’s record as a misidentification of an undescribed species, which he named A. watsoni. Significant works on these flies from the subantarctic New Zealand were also made by Harrison (1953, 1959, 1976). In the 1953 paper Harrison keyed all the species belonging to Macrocanace. He also discussed and illustrated Macrocanace littorea and described the new species Macrocanace antipoda, which he, however, synonymized later (Harrison, 1959) under Macrocanace australis (Hutton), after redescribing in detail both species of this genus. Moreover, a complete distributional and ecological (“associations” gathered from the label data) account concerning these two species was given by Harrison (1976) for the New Zealand subantarctic islands. Griffiths (1972)

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transferred the genus Macrocanace—together with Apetaenus and Listriomastax—to the family Tethinidae. In this connection, he particularly stated that “this subantarctic group [much later considered at the subfamilial level and named Apetaeninae by Mathis & Munari (1996)] shows all the apomorphous conditions of the male postabdomen which I ascribe to the groundplan of the Tethinidae”. The genus Macrocanace Tonnoir & Malloch was afterward (Mathis & Sasakawa, 1989) definitively downgraded to a junior synonym of Apetaenus Eaton. It should be stressed that Harrison, in all of his above-mentioned papers, regarded Macrocanace as belonging to the family Canacidae, while he ranked Apetaenus into Coelopidae, as various other authors also did in the past. In this connection, Harrison (1959) also designated the lectotype of Apetaenus litoralis Eaton, giving as distributional records the Kerguelen Islands and Macquarie Island, the latter place according to Womersley (1937). After redescribing Eaton’s type from the Kerguelen Islands, Harrison, in the same paper, inexplicably stated: “specimens from both localities [Kerguelen and Macquarie] have been examined and no differences seen between the two populations”. Conversely, Hardy (1962), who also considered Apetaenus as a coelopid fly, had quite a few perplexities about some of Harrison’s (1959) contradictory assertions and pointed out, contextually, the consistent, external differences between the two populations. Some interesting observations on Apetaenus watsoni Hardy from Macquarie Island were reported by Watson (1967) who also gave an exhaustive list of the composite habitats where the species commonly occurs, besides synthetically describing the history and the morphology of this species. Mathis & Munari (1996) gave a complete list of references for the world Apetaeninae in the framework of their “World Catalog of the family Tethinidae”. Unfortunately, that catalogue is woefully out of date because of many studies and reviews made since then. In these last years only occasional records of Apetaeninae from the subantarctic territories of Australia and New Zealand have been reported (Davies et al., 1997; Marris, 2000). Finally, D. K. McAlpine’s (2007) rearrangement of the Tethinids/Canacids taxonomic status made contextually clearer the position of the subfamily Apetaeninae, additionally suggesting an advisable subdivision of Apetaenus into subgenera.

The subgenera of Apetaenus Eaton and the peculiar subgenus Apetaenus s. str. D. K. McAlpine’s (2007) proposal to divide the genus Apetaenus into subgenera is herein accepted and further developed to include the subgenus Listriomastax Enderlein as well. This is necessary and desirable to better arrange all the species that are so well characterized morphologically and which need, therefore, to be grouped into inclusive taxa of subgeneric level. Following D. K. McAlpine’s (2007) arrangement of Macrocanace Tonnoir and Malloch and Apetaenus (s. str.) Eaton as subgenera of Apetaenus, I propose here to include the peculiar species Apetaenus enderleini Munari (= Listriomastax litorea Enderlein) into the subgenus Listriomastax Enderlein, formerly designated by Enderlein (1909) as a monotypic genus including the sole species litorea, whose specific name was very recently changed to enderleini (Munari, 2007). On the other hand, D. K. McAlpine (2007) said he did not have “material for deciding if there are grounds for retention of Listriomastax as a subgenus”. The subgenera Listriomastax plus Macrocanace would seem to form a monophyletic group, with the subgenus Apetaenus being its sister group on the basis of the external characters only. But, if we consider the morphological traits of the male terminalia, we can observe a very close affinity between the subgenera Apetaenus and Listriomastax rather than Macrocanace. It is perhaps significant that these two subgenera have evolved mainly in the same, strictly isolated and remote oceanic islands (fig. 15). Apart from microptery and redundance of the setal vestiture, the subgenus Apetaenus differs from the other two subgenera mainly for the absence of the very long, distinctive, posteroventral setae on the apical two-thirds of the fore femur in both sexes. Presumably these long setae were present as an apomorphic character in the common ancestor of the subfamily, but in time they became progressively lost in the lineage that resulted in Apetaenus (Apetaenus) litoralis s. lat.. Thus, I do

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believe that the absence of this character should not be interpreted as a putative plesiomorphic state with respect to the groundplan of the subfamily, but it should instead be regarded as a reversal. To corroborate this assumption, it should be stressed that I observed these characteristic setae also in two brachypterous individuals of Apetaenus (Listriomastax) enderleini. This would demonstrate that the development of this peculiar setal pattern of the fore femur is not directly influenced by the phenomenon of wing reduction (see further). As mentioned above, in the subgenus Apetaenus the micropterous condition is strictly associated to the remarkable redundance in the setal vestiture with respect to the groundplan of the subfamily, to the strikingly high degree of variation in the absence/presence, as well as in the development, of some main setae (Munari, 2007), and to the tarsal shortening. Similar or remarkably peculiar character state associations are also observed in some other subantarctic flies showing wing reduction (e.g. Helcomyzidae, Ephydridae, Sphaeroceridae). In particular Paractora dreuxi mirabilis Séguy, a helcomyzid fly from the Kerguelen province, exhibits an association of characters that is notably similar to that observed in the two subspecies Apetaenus (Apetaenus) litoralis marionensis n. ssp. and A. (Apetaenus) litoralis watsoni Hardy n. stat.. Most of these character states associated with microptery do not have any apparent adaptive significance, with the possible exclusion of the tarsal reduction, which is likely an adaptation for a lapidicolous life. Thus, the meaning of the very peculiar setal vestiture (in particular of the male abdomen) in the subgenus Apetaenus s. str. is at present rather obscure and puzzling, also because some other subantarctic, micropterous flies belonging to different families do not exhibit a significant redundance in the body setulation. We can speculate that the selective pressure that has acted on both wing reduction and tarsal shortening could have had, as a collateral cascade effect, the evolution of a peculiar setal vestiture, possibly generated by developmental constraints occasionally shared by a few other flightless flies (e.g. Paractora dreuxi mirabilis Séguy). Our present, limited knowledge on the physiology, genetics and developmental biology of these insects prevents us from discussing this hypothesis further.

Key to the world subgenera of Apetaenus 1. Micropterous species with vestigial wings and halters; thorax and abdomen (in particular the latter) strikingly setose (fig. 11) or with dense, long villosity (fig. 12); fore femur in both sexes with no long setae on distal two-thirds; tarsi stumpy ............................................................................subgenus Apetaenus Eaton -. Macropterous species (except for some rare, localized individuals of A. (Listriomastax) enderleini which exhibit brachy- and microptery) with fully developed wings and halters; thorax (except for main, long setae) and abdomen poorly setose; fore femur in both sexes with 2–4 widely spaced, very long, forward curved, postero-ventral setae on distal two-thirds; tarsi slender (more or less shortened in specimens showing wing reduction) .............................................................................................................................2 2. Vein R1 bare; postpronotal seta lacking; preabdomen of female strongly physogastric, with syntergite 1+2 deeply split medially; wing reduced in some isolated specimens .......... subgenus Listriomastax Enderlein -. Vein R1 setulose; postpronotal seta strong; preabdomen of female moderately physogastric, with syntergite 1+2 never split medially; no wing reduction .................. subgenus Macrocanace Tonnoir and Malloch Three species of the genus Apetaenus Eaton are known from the subantarctic islands of Australia and New Zealand (fig. 15). A. litoralis s. lat. is the only species also occurring in the westernmost archipelagos of the Kerguelen Biogeographical Province (subantarctic Indian Ocean), although it is represented in the Australian area by a distinctive subspecies formerly described by Hardy (1962) as a valid, endemic species inhabiting Macquarie Island.

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Key to species of Apetaeninae from the Australian and New Zealand subantarctic islands 1. Micropterous species with vestigial wings and halters; thorax and abdomen (especially the latter) of both sexes densely long haired; dorsocentral setae 0+1; fore femur with no long postero-ventral setae on apical two-thirds; tarsi stumpy ......................................... Apetaenus (Apetaenus) litoralis watsoni Hardy n. stat. -. Macropterous species with fully developed wings and halters; thorax and abdomen (especially the latter) of both sexes never long haired; dorsocentral setae more numerous, at least 1+3 setae present; fore femur with 2–4 very long, postero-ventral setae on apical two-thirds; tarsi slender ...........................................2 2. Body length of male 3.5 mm; postocellar setae absent; 1+3 dorsocentral setae; anepisternum with only 1, isolated, long, posteromedian seta, upper and lower setae absent (fig. 6); wing distinctly patterned, with numerous both elongated and rounded, pale whitish spots (figs. 9–10); dorsal surface of vein R1 bearing 10–14 spinelike setae; mid and hind femora with 1 or more (generally 2–3) long and strong, antero-dorsal setae on distal half, noticeably arising from the short setular vestiture; male terminalia (figs. 3–4) large; epandrium simple, with no ventral lobe apically; surstylus relatively short and stumpy, with subtriangular apical part (lateral view), rodlike caudally, with characteristic, yellowish, subcylindrical protuberances on its strongly indented, inner apical edge, each protuberance bearing one spinelike seta arising from the internal cavity; cercus markedly elongated, distinctly angulated on inner, apical edge; distiphallus noticeably enlarged, relatively short and thickset .......................... Apetaenus (Macrocanace) littoreus (Hutton)

Taxonomic account Apetaenus (Apetaenus) litoralis watsoni Hardy, 1962 n. stat. Apetaenus watsoni Hardy, 1962: 965 [Macquarie Island. Hurd Point; HT %, ANIC].—Womersley, 1937: 75 [as Apetaenus litoralis Eaton, citation, Macquarie Island].—Watson, 1967: 28–29 [ecology].—Harrison, 1976: 127 [citation, Macquarie Island].—Mathis and Sasakawa, 1989: 667 [Australasian/Oceanian catalog].—Mathis and Munari, 1996: 8 [World catalog].—Davies et al., 1997: 456–457 [citation, Macquarie Island, Bishop Island].

Distribution. Australasian/Oceanian: hitherto only known from Bishop Island and Macquarie Islands. Material examined. Eight paratypes (4%% 4&& from Macquarie Island: Hurd Point, Nuggets Point, North Head) of this subspecies were examined from the collections of BMNH and ANIC—six specimens from the latter collection are now in the author’s collection (MCNV). All these paratypes are in rather good condition. Habitat and microhabitats. A thalassobiont species with a marked preference for microdetritivorous, polysaprophagous and possibly coprophagous diet. It seems to be strictly associated as a polysaprophagous insect to sea bird nests and penguin colonies. It was recorded in the literature from the following microhabitats: on Colobanthus muscoides cushions, algae on coastal rocks, under rookery stones and rocks (Hardy, 1962; Watson, 1967); coastal rocks of the upper Porphyra zone amongst red, brown and green algae, rotting kelp, closely associated with areas around rookeries where there is plenty of rotting organic matter (Watson,

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1967); on Puccinellia macquariensis on rocks close to the sea (Watson, 1967; Harrison, 1976); under loose rocks or in rock crevices, bare soil, bird nests (Davies et al., 1997). Some interesting ecological observations made by Watson (1967) are as follows:”These brachypterous flies [indeed they are strictly micropterous flies] are quite abundant throughout the year. They can be seen walking slowly over the algae or bare rock in the upper Porphyra zone; pairs in copulation are commonly seen throughout the year. Less frequently, flies can be found walking over pebbles on the beach, and in clusters on pieces of kelp and under stones and driftwood. In penguin rookeries they mass together under stones in the well manured mixture of mud and feathers. Here the immature stages lie in the wet mud; on the coastal rocks they are found entangled in the fine, filamentous green alga (Rhizoclonium sp.), amongst the fronds of Porphyra umbilicalis and in crevices of the rock. The pupae attach themselves to the rock or alga by a secretion”.

Apetaenus (Macrocanace) australis (Hutton, 1902) (figs. 1–2, 5, 7–8) Ochtiphila australis Hutton, 1902: 174 [Campbell Island; HT %, NZAC (originally in the Cawthron Institute collection). However, the holotype does not appear in the list of the “Primary type specimens in the New Zealand Arthropod Collection (NZAC): Diptera” (Web Version 1 – June 1997)]. Macrocanace australis.—Tonnoir and Malloch, 1926: 5 [generic combination].—Harrison, 1976: 142–143 [citation, southern islands of New Zealand subregion]. Apetaenus australis.—Mathis and Sasakawa, 1989: 667 [generic combination, Australasian/Oceanian catalog].—Mathis and Munari, 1996: 7 [World catalog].—Marris, 2000: 193 [citation, Campbell Island].—D.K. McAlpine, 2007: 30, 36–37 [SEM photographs of lower face and adjacent parts, fore basitarsus, acropod, and part of costa]. Macrocanace antipoda Harrison, 1953: 276 [Antipodes Island: Ringdove Bay (spider’s web); HT &, AMNZ]; 1959: 251 [synonymy].

Distribution. Australasian/Oceanian: Antipodes, Auckland, Campbell, and Snares islands. Material examined. 53%% 71&& 2 undet. sex—NZAC—from Antipodes (Reef Pt, Stella Bay), Auckland (Adams Island), Campbell (Beeman Camp, De la Vire Pt, Tucker Cove), and Snares Islands (Biological Station, Seal Cove, Tern Point) were examined, all of them formerly determined and published as Macrocanace australis (Hutton) by Harrison (1976). Other specimens examined. NZAC—Auckland Islands (Exp. 1972–73): Camp Cove, littoral rocks, seaweed beds, sweeping rocky shore, 8.ii. and 17.ii.1973, J. S. Dugdale, 6 %% 6 &&; Enderby Island, West of Sandy Bay, around shag [Phalacrocoracidae] nests on cliff faces, 26.ii.1973, J. S. Dugdale, 1 %; Rose Island, on coastal rocks, 26.ii.1973, J. S. Dugdale, 1 &; Tagua Bay, Carnley Harbour, supralittoral, 11.ii.1973, J. S. Dugdale, 2 &&. Snares Islands: Rima Islet, Western Chain, seal dung on rocks, 5 m, 21.xi.1976, J. W. Early, 1 %; Sinkhole Gut, rotting Durvillea, high eulittoral zone, seal faeces on supralittoral rock, 14.vi. and 28.xii.1976, J. W. Early, 2 %% 1 &; Station Cove, rotting Durvillea, seal dung on supralittoral rocks, at edge of mid-eulittoral tide pool, 25.ii.1975, 26.xi.1976, 9.i.1977, J. W. Early, D. S. Horning, 4 %% 4 &&. LUNZ—Antipodes Island: Anchorage Bay, sweeping around rocks by penguin colony, 3.xi.1995, A. R. McIntosh, 3 %%; Hut Cove, ex yellow pan trap among herbs and ferns on coastal cliffs, 2-17.xi.1995, J. W. M. Marris, 2 &&. Habitat and microhabitats. A thalassobiont fly with the same ecological preferences as the preceding species. It was recorded in the literature from the following microhabitats: on shore, ex spider web (Harrison, 1959); supralittoral beach drift, tussock, seaweed, seal and sea elephant wallows, shore rocks and cliffs, on supralittoral vegetation (Colobanthus, Stilbocarpa, Bulbinella, Hebe elliptica), kelp on beach, Enteromorpha, Bostrychia, algae, in supralittoral crustose lichen, Rockhopper Penguin rookery, on rocks in rookery, albatross carrion (Harrison, 1976). The female type of Macrocanace antipoda (= A. australis) was recorded by Harrison (1953) from a spider’s web. Additionally, the following habitats and microhabitats are herein newly

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reported (see material examined): high eulittoral zone, supralittoral, littoral rocks, seaweed beds, around shag nests on cliff faces, rotting Durvillea, seal faeces on supralittoral rock, at edge of mid-eulittoral tide pool, around rocks by penguin colony, ex yellow pan trap among herbs and ferns on coastal cliffs.

FIGURES 1–2. Apetaenus (Macrocanace) australis (Hutton). 1. Male terminalia lateral view; 2. ditto, caudal view. Scale bar = 0.1 mm.

Remarks. This species differs from the related A. (Macrocanace) littoreus mainly by the following characters: body length of male 3.5 mm; postocellar setae absent; postocular setae hardly visible, strikingly to moderately tiny; face vertically flattened in lateral view; clypeus well exposed forward though not so strongly protrudent as that of preceding species, its distal margin about vertically beneath half of postpedicel; scutum pale grey to brownish, generally bearing 3 distinct, longitudinal, brown stripes; 1+3 dorsocentral setae (rare specimens exhibit variation, bearing 1 additional seta or, even, 1 additional pair of setae); disc of scutellum with few, scattered, marginal, tiny (sometimes microscopical) setulae besides four long and strong scutellar setae; proepisternal seta moderately long and curved; anepisternum with only 1, isolated, long, posteromedian seta, upper and lower setae absent (fig. 6); wing distinctly patterned, with numerous both elongated and rounded, pale whitish spots (figs. 9–10); dorsal surface of vein R1 bearing 10–14 spinelike setae; mid and hind femora with 1 or more (generally 2–3) long and strong, antero-dorsal setae on distal half, noticeably arising from the short setular vestiture; male terminalia (figs. 3–4) large; epandrium simple, with no ventral lobe apically; surstylus relatively short and stumpy, with subtriangular apical part (lateral view), rodlike caudally, with characteristic, yellowish, subcylindrical protuberances on its strongly indented, inner apical edge, each protuberance bearing one spinelike seta arising from the internal cavity; cercus markedly elongated, distinctly angulated on inner, apical edge; distiphallus noticeably enlarged, relatively short and thickset; female abdomen only slightly telescopically retractile; tergite 1 of female as long as or slightly shorter than half of tergite 2, with diaphanous, ventro-lateral margins; sternite 2 as long as tergite 2, sclerotized, with subparallel, spinulose, longitudinal borders; sternite 3 with a few long setae on its sclerotized borders; sternites 4–7 each bearing a pair of relatively long setae on posterior half.

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FIGURES 3–4. Apetaenus (Macrocanace) littoreus (Hutton). 3. Male terminalia lateral view; 4. ditto, caudal view. Scale bar = 0.1 mm. The arrow indicates a magnified detail of the surstylus apical portion.

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FIGURES 5–6. Chaetotaxy of anepisternum. 5. Apetaenus (Macrocanace) australis (Hutton); 6. Apetaenus (Macrocanace) littoreus (Hutton). Scale bar = 0.5 mm.

Subdivision of Apetaenus (Apetaenus) litoralis Eaton into subspecies Eaton’s species is widely distributed in the subantarctic archipelagos, from Macquarie Island, south of New Zealand, to Marion Island, the westernmost island of the Kerguelen Biogeographical Province. After studying this species from various subantarctic sites, I have concluded that this species includes at least three distinct and easily recognizable geographical races, which are herein formally ranked at the subspecific level (see further). Apetaenus litoralis is a flightless, micropterous fly strictly dependant on the nature of the soil microhabitats, like many other terricolous/lapidicolous arthropods, such as spiders and beetles. It is likely that some events of microspeciation can have taken place indeed in those organisms characterized by very scarce vagility, that is with a weak capability of dispersal, rather than in strongly flying insects which are influenced mainly by passive—e.g. storm winds—and active dispersal. Womersley (1937) recorded Apetaenus litoralis Eaton from Macquarie Island, the easternmost place in the distribution of this species known, at that time, only from the islands of the Kerguelen Province. Much later, Hardy (1962) stated that the specimens recorded by Womersley in his paper of 1937 belonged indeed to a new species, A. watsoni, described by Hardy himself in the same paper of 1962. Indeed both of these authors were right. The former had recognized in the examined specimens the peculiar morphological and chaetotactical traits which noticeably typify Eaton’s species, while the latter noticed that the individuals inhabiting Macquarie Island exhibited some consistent features that allowed separating them from the typical A. litoralis Eaton. After dissecting the male postabdomen of specimens of A. litoralis from Marion, Crozet, Kerguelen, and Macquarie islands, it was immediately clear to me that all of them belonged to the same species, although they were typified by such external characters that allowed subdividing them into three well differentiated subspecies, namely A. litoralis marionensis n. ssp., described herein from Marion Island, A. litoralis litoralis Eaton from the numerous other islands of the Kerguelen Biogeographical Province, and A. litoralis watsoni Hardy n. stat. from the easternmost Macquarie Island. On the other hand, it should be also stressed that Munari (2007) had already anticipated some doubts about the presumed validity of Hardy’s species.

Key to subspecies of Apetaenus (Apetaenus) litoralis Eaton 1. Body strongly bristly, with setal vestiture shaggy and piceous, in particular abdomen of male exclusively

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bearing several, long, strong, black setae (fig. 11); abdomen of female with sparse, noticeably shorter, black setae; head markedly setulose, often with supernumerary setae and setulae; postocellar setae variable, generally lacking, if present strongly cruciate; seta of postpronotal lobe variable, generally lacking; dorsocentral setae 1+2; katepisternum generally bearing 2–4 long setae on upper part; tergite 2 of female bearing scattered, short, hispid setae latero-ventrally. (Crozet, Kerguelen, ?Heard islands) ....................... ........................................................................................................ A. (Apetaenus) litoralis litoralis Eaton -. Body covered with very characteristic, long, fine, dense, soft, apparently light brown villosity (indeed with blackish setae showing noticeably golden reflections), never shaggy and piceous; abdomen of both sexes more or less densely, softly long haired, with no distinct setae present (fig. 12); head usually without supernumerary setae and setulae; postocellar setae generally present, strongly cruciate, one of two sometimes hairlike; seta of postpronotal lobe variable, often present, strong or hairlike; dorsocentral setae variable in number; katepisternum bearing at most 2 (rarely 3) long setae on upper part; tergite 2 of female bearing several, long, dense, fine setae latero-ventrally .............................................................................2 2. Postpronotal seta strongly variable, present to absent; dorsocentral setae 1+2; costa of reduced wing generally with noticeably long and strong setae on alar apex; abdomen of female sparsely long haired; tergite 2 of female bearing both fairly long villosity and moderately short setae, anteriad and posteriad respectively, latero-ventrally. (Marion, ?Prince Edward islands) .... A. (Apetaenus) litoralis marionensis n. ssp. -. Postpronotal seta generally present; dorsocentral setae 0 + 1 (in extremely rare individuals 1 long and markedly subtle presutural also present); costa of reduced wing shaggy, bearing several, close, long setae on entire length of vein; abdomen of female thickly long haired; tergite 2 of female only bearing dense, long villosity latero-ventrally. (?Bishop, Macquarie islands) ....................................................................... ............................................................................................ A. (Apetaenus) litoralis watsoni Hardy n. stat. The question marks placed before the names of a few above-recorded islands mean that I have seen no specimens from those oceanic sites and I am therefore unable to confirm with certainty the subspecific status of the populations inhabiting there.

Apetaenus (Apetaenus) litoralis marionensis new subspecies Type material. Holotype %, [printed labels] “Janvier // I. Marion / baie Jeannel // Muséum Paris / Croisière du / Bougainville / R. Jeannel I–II 1939 // [printed red label] Holotypus / Apetaenus litoralis / marionensis n. ssp. % / L. Munari des. 2007 // [printed white label] subgenus / Apetaenus / Eaton”. The specimen is in excellent condition, except for a few tarsal segments lacking, and is double mounted, micropinned ventro-dorsally. The holotype is deposited in MNHN. Paratypes: same data as holotype, 4 %% 3 &&; Marion Island, i–ii.1952, R. W. Rand, 13 %% 7 && (one male specimen det. by Séguy in 1953 as Apetenus [sic] litoralis Eat.). Paratypes (double mounted, micropinned ventro-dorsally) from “Bougainville Expedition” are deposited in MNHN, except for one male preserved in the author’s collection (MCNV); paratypes (double mounted, glued to a card slip) collected by R. W. Rand are deposited in NMSA, except for a pair preserved in the author’s collection (MCNV). Almost all the paratypes preserved in NMSA are unfortunately in poor condition due to an inadequate, old preparation by using excessive glue to fix them to the card slip. Description. Similar to A. (Apetaenus) litoralis litoralis Eaton, agreeing with descriptions of that species (Harrison, 1959; Munari, 2007), except as indicated below. Size. Body length 3.60–3.95 mm; wing length 0.42–0.53 mm. Coloration. Ground colour mostly darker, dark brown to blackish. Head. Eye roundish to slightly oblong, its longest diameter about two times as long as genal height; setal

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vestiture of head very long and strong. Thorax. A few specimens exhibit considerably long main setae, which are sometimes thin and characteristically wavy on their distal half; setulae very long and numerous, in particular on anterior half of mesonotum, forming dense, soft, sometimes ruffled, pubescence; costal vein of the reduced wings with numerous, strikingly long, close, apical setae. Abdomen. Entirely covered with a very characteristic and distinctive setal vestiture (fig. 12) formed by a multitude of considerably long, dense, sometimes ruffled and tuft-forming, thin hairs, distinctly more numerous on abdomen of male specimens, where they constitute an evenly soft pubescence, quite similar to that of A. litoralis watsoni Hardy. No distinct, strong setae are present. Distribution. Subantarctic Indian Ocean: Marion Island. Etymology. The subspecific epithet, marionensis, is a toponymic Latin adjective, referring to the subantarctic island where the type series was collected. Remarks. The main, consistent feature distinguishing this new subspecies from the nominal subspecies is the abdomen being densely and softly haired (fig. 12) rather than markedly bristly (fig. 11). Unlike the nominal subspecies, no strong abdominal seta is consistently present.

Conclusions A phylogenetic analysis of the world Apetaeninae is at present rather premature. Any conclusion concerning their evolution on the remote, subantarctic archipelagos would be forcedly incomplete and possibly misleading. In fact, although we know these flies exhaustively from both the Kerguelen Biogeographical Province and New Zealand-Australian subantarctic islands, no species is known so far from the subantarctic territories of South America (fig. 15), viz. Southern Patagonia (including Tierra del Fuego Island), Falkland, South Georgia, South Sandwich, Austral Shetland, South Orkney islands, and the easternmost, oceanic Bouvet Island (Bouvetøia). Since many of these islands are overseas British possessions, I hopefully supposed that a number of specimens could be found in the collection of the Natural History Museum, London, as a result of British, subantarctic, entomological expeditions carried out in the past. Unfortunately, I received from the British colleague Mr. N. Wyatt, the curator of Diptera of that museum, the unpleasant notice that no specimens of Apetaeninae from the subantarctic lands of South America had been found by him in the collection of the London museum. I also got the same kind of answer from Dr. W. N. Mathis as for the Diptera collection at the Smithsonian National Museum of Natural History, Washington. Hopefully awaiting to find some material available for examination from collections of South American and Norwegian (Bouvet Island is a dependent area of Norway) scientific institutions, I remain particularly trustful to see a few specimens of these flies inhabiting the cold, rocky littorals of those remote sites. This expectation is encouraged by the fact that the latitudinal, climatic, and environmental characteristics of these oceanic places north of 60° S (except for the South Orkney Islands which are 60°35’ S) are, to a large extent, the same in all other islands around Antarctica. Apetaenus species also seem to be strictly dependent on the scarce competition for food and predation occurring in the small, isolated, insular environments (Munari, 2007). This, in addition to a milder climate due in particular to the presence of large masses of emerged lands, are possibly the factors that account for their absence in the southern seashores of New Zealand, although these maritime environments are located at the same latitude of the archipelagos of the Kerguelen Biogeographical Province, where, conversely, the Apetaenus species are well represented. Two difficult questions arise now: a) how were Apetaenus species able to occupy such isolated, oceanic places so distant from each other? b) where was the primary, ancestral area of the Apetaeninae located? We know that no record of Apetaeninae and closely allied groups has been reported in the literature from the

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southern continental littorals of South Africa, Australia and New Zealand (as for Southern Patagonia no specific research has been carried out so far). It is reasonable to suppose that these flies spread from an ancient Gondwanan area (see further) towards the archipelagos around Antarctica. These island groups have different ages of formation/emergence. For instance, a few subantarctic islands, such as Marion and Macquarie, have had a rather recent volcanic origin (Marion, ca. 500.000 years ago) or recent emergence of a ridge formed by very ancient oceanic crust and rocks from the ocean’s surface (Macquarie, ca. 600.000–700.000 years ago) (Meiklejohn, 2005; Seppelt & Connell, 2006). Other islands, such as Kerguelen and Crozet, have instead a much more ancient geological origin. Methods of dispersal between islands may have been via wind, particularly for the macropterous species, or the eggs and pupae of these flies were probably conveyed by sea-birds in relatively recent times. But, dispersal from which ancestral area? It is possible the ancestors of the subfamily began their evolution and subsequent dispersal in the original, northernmost Gondwanan position of Antarctica. Around 23 million years ago, when the Drake Passage fully opened between Antarctica and South America (Lyle et al., 2007; Scher & Martin, 2006), which resulted in the Antarctic Circumpolar Current, the flies possibly began a northwards, circumpolar dispersal towards the oceanic islands with a milder climate. This slow but progressive dispersal maybe happened when the polar ice commenced to spread everywhere, replacing the forests, as well as the coastal vegetation, that then covered the Antarctic continent. Of course, this hypothesis can hopefully be corroborated only when possible species from the subantarctic South America will become available for examination. This vast area constitutes at present a disappointing biogeographical gap (fig. 15) that does not allow to properly infer about the presumed origin and distribution of the subfamily Apetaeninae.

Acknowledgements I wish to express my deepest gratitude to the following scientists, curators, technicians and other people for their irreplaceable support or for allowing me to study the fly material preserved in the collections of their institutes: Prof. S. L. Chown (Stellenbosch University, Matieland, South Africa), Dr. T. K. Crosby (New Zealand Arthropod Collection, Auckland, New Zealand), Dr. C. Daugeron and Mr. E. Delfosse (Muséum National d’Histoire Naturelle, Paris, France), Dr. G. Fusco (Università degli Studi di Padova, Padova, Italy), Dr. J. W. M. Marris (Lincoln University, Canterbury, New Zealand), Dr. B. R. Stuckenberg, Dr. M. Mostovski, and Ms. P. Birkett (Natal Museum, Pietermaritzburg, South Africa), Ms. T. de Roy (Takaka, New Zealand) for kindly authorizing the publication of a few photographs taken by her in the subantarctic archipelagos [Ms. Tui De Roy is recognized internationally as one of the world's great wildlife photographers], Prof. C. H. Scholtz (University of Pretoria, Pretoria, South Africa), Mr. N. Wyatt (The Natural History Museum, London, U.K.), Dr. D. K. Yeates and Mr. C. Manchester (ANIC–CSIRO, Canberra, Australia). My sincerest thanks are also due to all the employees of the technical and administrative staff of the Natural History Museum,Venice, as well as to their Director Dr. E. Ratti, for the friendly, logistic support. Finally, particular thanks go to Dr. D. K. McAlpine (Australian Museum, Sydney, Australia), Dr. W. N. Mathis (Smithsonian National Museum of Natural History, Washington D. C., United States), and Dr. L. V. Knutson (Gaeta, Italy) for critically reviewing the manuscript.

References Davies, K.F., Greenslade, P. & Melbourne, B.A. (1997) The invertebrates of sub-Antarctic Bishop Island. Polar Biology, 17, 455–458. Enderlein, G. (1909) Die Insekten des Antarktischen Gebiets. In, von Drygalski, E. (ed.), Deutsche Südpolar-Expedition

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1901-1903 im Auftrage des Reichamtes des Innern. Band X. Zoologie II. 4(1908), 361–528. Griffiths, G.C.D. (1972) The Phylogenetic Classification of Diptera Cyclorrhapha, with Special Reference to the Structure of the Male Postabdomen. Series Entomologica, 8, 1–340. The Hague: W. Junk, N.V. Hardy, D.E. (1962) Insects of Macquarie Island. Diptera: Coelopidae. Pacific Insects, 4(4), 963–971. Harrison, R.A. (1953) The Diptera of the Antipodes and the Bounty Islands. Transactions of the Royal Society of New Zealand, 81(2), 269–282. Harrison, R.A. (1959) Acalypterate Diptera of New Zealand. Bulletin of the New Zealand Department of Scientific and Industrial Research, 128, 1-382. Wellington. Harrison, R.A. (1976) The Arthropoda of the Southern Islands of New Zealand (9). Diptera. Journal of the Royal Society of New Zealand, 6(2), 107-152. Hutton, F.W. (1902) On a small collection of Diptera from the Southern Islands of New Zealand. Transactions of the New Zealand Institute, 34, 169–175. Lyle, M., Gibbs, S., Moore, T.C. & Rea, D.K. (2007) Late Oligocene initiation of the Antarctic Circumpolar Current: Evidence from the South Pacific. Geology, 35(8), 691–694. Marris, J.W.M. (2000) The beetle (Coleoptera) fauna of the Antipodes Islands, with comments on the impact of mice; and an annotated checklist of the insect and arachnid fauna. Journal of The Royal Society of New Zealand, 30(2), 169–195. Mathis, W.N. & Munari, L. (1996) World Catalog of the Family Tethinidae (Diptera). Smithsonian Contributions to Zoology, 584, iv+1–27. Mathis, W.N. & Sasakawa, M. (1989) Family Tethinidae. In: Evenhuis, N.L. (ed.), Catalog of the Diptera of the Australasian and Oceanian Regions, pages 667–668, 803–804. Honolulu: E.J. Brill and B.P. Bishop Museum special publication 86, 1155 pages. McAlpine, D.K. (2007) The Surge Flies (Diptera: Canacidae: Zaleinae) of Australasia and notes on Tethinid-Canacid morphology and relationships. Records of the Australian Museum, 59(1), 27–64. McAlpine, J. F. (1981) Morphology and Terminology—Adults. In: McAlpine, J. F. et al. (eds.), Manual of Nearctic Diptera, 1: 9–63. Ottawa: Research Branch, Agriculture Canada, Monograph 27. Meiklejohn, I. (2005) Marion Island Research. Department of Geography, Geoinformatics and Meteorology, University of Pretoria. Web: http://www.up.ac.za/academic/geog/marion_island.html Merz, B. & Haenni, J-P. (2000) Morphology and terminology of adult Diptera (other than terminalia). In: Papp, L. & B. Darvas (eds.), Contributions to a Manual of Palaearctic Diptera, 1, 21—51. Science Herald, Budapest. Munari, L. (2007) Studies on the Canacidae (Diptera), subfamily Apetaeninae. I. Apetaenus enderleini, nomen novum for Listriomastax litorea Enderlein, 1909, with remarks on the chaetotaxy, morphology, and habitats of the Apetaeninae from the Kerguelen Biogeographical Province. Zootaxa, 1542, 21–34. Scher, H.D. & Martin, E.E. (2006) Timing and climatic consequences of the opening of Drake Passage. Science, 21 April 2006, Vol. 312, no. 5772, 428–430. Séguy, E. (1940) IV. Diptères. In: Jeannel, R. (ed.), Croisière du Bougainville aux îles australes françaises. Mémoires du Muséum national d’Histoire naturelle, new series, 14, 203-267. Seppelt, R. & Connell, D. (2006) Macquarie Island. Australian Government, Department of the Environment and Water Resources, Australian Antarctic Division. Web: http://www.aad.gov.au/ default.asp?casid=1978 Stuckenberg, B.R. (1999) Antennal evolution in the Brachycera (Diptera), with a reassessment of terminology relating to the flagellum. Studia dipterologica, 6(1), 33–48. Tonnoir, A.L. & Malloch, J.R. (1926) New Zealand Muscidae Acalyptratae. Part I.—Ephydridae. Records of the Canterbury Museum, 3(1), 1-26. Watson, K.C. (1967) The Terrestrial Arthropoda of Macquarie Island. Australian National Antarctic Research Expeditions Scientific Reports, Series B (1) Zoology, 99, i–xii + 1–90. Womersley, H. (1937) Diptera. In: Reports of the British-Australian-New Zealand Antarctic Research Expedition 1929– 31, B, 4(3), 59–79.

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FIGURES 7–12. 7–10. Wing (N.B.: the seeming sinuosity of the costal vein, as it appears in some of these photographs, is exclusively due to a defective slide preparation). 7. Apetaenus (Macrocanace) australis (Hutton) from the Antipodes Islands; 8. ditto from the Snares Islands; 9. Apetaenus (Macrocanace) littoreus (Hutton) from the Antipodes Islands; 10. ditto from the Bounty Islands. 11–12. Abdomen of male dorsally. 11. Apetaenus (Apetaenus) litoralis litoralis Eaton; 12. Apetaenus (Apetaenus) litoralis marionensis n. ssp.

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FIGURES 13–14. Two typical landscapes of the subantarctic Bounty Island showing the rocky and impervious coasts populated by several colonies of sea-birds. These are the elective environments of the Australian and New Zealand subantarctic species of Apetaenus. (Photo Courtesy of Tui de Roy).

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FIGURE 15. Distributional map of the subfamily Apetaeninae (as for the insular toponyms, see the text as well as the distributions given in Munari, 2007). Legend: geographical area delimited by a thick grey line = biogeographical gap (no species has been recorded so far); = A. (Apetaenus) litoralis litoralis Eaton; = A. (Apetaenus) litoralis marionensis n. ssp.; = A. (Apetaenus) litoralis watsoni Hardy;  = A. (Listriomastax) enderleini Munari;  = A. (Macrocanace) australis (Hutton); = A. (Macrocanace) littoreus (Hutton).

F

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