Pseudorhicnoessa longicerca, Munari, Lorenzo, 2014

Munari, Lorenzo, 2014, New Indo-Pacific species of Dasyrhicnoessa Hendel, 1934 and Pseudorhicnoessa Malloch, 1914 (Diptera: Canacidae: Tethininae), Zootaxa 3784 (3), pp. 281-293 : 288-291

Pseudorhicnoessa longicerca sp. nov.

( Figs 7–9 )

Diagnosis. This species is distinguished from congeners mainly by the following characters of the male terminalia: anterior surstylus distinctly curved backward, rounded apically, finger-like in lateral view, paddle-shaped in anterior and posterior views, bearing several long setae on ventral margin; posterior surstylus sickle-like (falciform) in lateral view, roughly subtriangular in posterior view; cercus conspicuously developed, slightly longer than anterior and posterior surstyli length, membranous part of both cerci apparently fused subapically, becoming widely separated and characteristically bifid at apex.

Description. Size. Body length 3.08–3.52 mm, wing length 2.00– 2.20 mm.

Habitus. Robust fly with dark grey (thorax) to brown (abdomen) body; legs mostly yellow, with apical parts of hind femur and tibia strongly infuscate; setal vestiture black; wing yellowish grey; male with large, globoid, broadly exposed epandrium.

Head. Slightly higher than long; vertex and occiput cinereous, frons yellow, face apparently membranous, invested with pale whitish microtomentum, gena faintly yellow to whitish, evenly microtomentose; postocellar setae inclinate, somewhat spaced, about as long as dorsal postocular seta; medial vertical seta oriented inward, strong, about as long as lateral vertical seta, which is lateroclinate; postocular setae arranged in 2 distinct rows; ocellar triangle bearing some minute setulae between and behind ocelli, in addition to a pair of long, strong ocellar setae; 3 long fronto-orbital setae, posterior ones distinctly lateroclinate, anterior seta slightly reclinate; frontoorbitals intermixed with a few lateroclinate and inclinate short setulae; 3 pairs of proclinate and more or less slightly inclinate interfrontal setae, intermixed with some short additional setulae, anterior pair with setae weaker and shorter than posterior pairs; antenna yellow, with basal flagellomere widely dark brown; arista brown to black, microscopically pubescent; eye apparently glabrous, large, subcircular to slightly oblong, its vertical diameter about 4.6 times as long as genal height (holotype); 6 – 7 peristomal setae, including pseudovibrissa, increasingly longer towards vibrissal angle; clypeus distinctly exposed; mouthparts yellow (palpus) to brownish (proboscis), labellum slightly shorter than buccal cavity length.

Thorax. Blackish in ground colour, invested with grey microtomentum, excepting postpronotal lobe which is mostly yellow, whitish if viewed dorsally, and notopleuron faintly to distinctly yellowish; 1+3 dorsocentral setae, posterior one very long; acrostichal setulae arranged in 7 – 8 rows; acrostichal prescutellar setae noticeably developed; 3 postpronotal setae intermixed with several short setulae, each major seta with a different orientation; 1 presutural; 2 notopleurals; 2 supra-alars, ventral one distinctly shorter and weaker; 2 postalars; several rows of short setulae between dorsocentrals and the lateral side of scutum; scutellum with 2 pairs of long setae, several minute setulae on disc and on lateral margins; 1 proepisternal; 1 proepimeral; anepisternum densely setulose, with 2 long postero-marginal setae and 1 dorsally oriented, posterodorsal seta; katepisternum sparsely setulose, with 1 long, strong seta on posterodorsal margin; anepimeron and meron without setae and setulae. Legs. Mostly yellow, excepting apical parts of hind femur and tibia, and a patch on antero-apical area of forefemur, which are strongly dark brown; distal 2 tarsomeres distinctly black to brown infuscate; coxae with several long setae; forefemur slightly swollen, with some long setae dorsally and posterodorsally, a posteroventral row of long, fine setae on entire length of femur, an anteroventral row of fine, close, long setae on proximal two thirds, apical third bearing a ctenidial comb of short, close, pointed spinulae; foretibia and foretarsus evenly setulose; male mid femur with some anterior setae on distal half, a dense row of robust, long setae posteroventrally; mid tibia with 3 – 4 posterodorsal setae, 1 – 2 anterior to anterodorsal setae, 1 apicoventral, spur-like, long and strong seta; hind femur distinctly swollen in males, with 1 – 2 anterior setae approximately in the middle and 3 – 4 dorsal setae on apical half, decreasing in length towards apex of femur; hind tibia bearing 2 dorsal to subdorsal, 2 anterodorsal, 2, sometimes 3, posterodorsal setae; 1 apicoventral spur-like seta. Wing. Veins brownish yellow, membrane yellowish grey; alula with fringe formed by several, long, grey setae; subcostal break deeply notched; first costal sector bearing 2 long apical setae; costal vein reaching end of R4+5; R2+3 and R4+5 slightly divergent distally; R4+5 and M1 subparallel on distal half; crossvein r-m ending approximately near middle of cell dm; crossvein dm-cu less than one third of the length of last section of CuA1; halter yellowish.

Abdomen. Brown, invested with pale grey microtomentum, bearing several setulae dorsally and laterally, and long postero-marginal setae; tergite 6 bare dorsally, bearing a row of 5 – 6 setae on postero-lateral margin; syntergite 1+2 and tergite 3 with obvious postero-marginal yellowish stripes; sternites yellow, pubescent. Male terminalia. Epandrium very large, globoid, densely setulose; anterior surstylus distinctly curved backward, rounded apically, finger-like in lateral view (fig. 7), paddle-shaped in anterior (fig. 9) and posterior views, bearing several long setae on ventral margin; posterior surstylus sharply sickle-like in lateral view (fig. 7), roughly subtriangular in posterior view (fig. 8); cercus conspicuously developed, slightly longer than length of anterior and posterior surstyli (figs 7– 8), membranous part of both cerci apparently fused subapically, becoming widely separated and characteristically bifid at apex (fig. 8); phallus noticeably widened on proximal two thirds, ribbon-like on apical third; widened part strongly pubescent ventrally, minutely pubescent (papilla-like setulae) dorsally; ejaculatory apodeme and phallapodeme as usual for the subfamily. Female terminalia. Postabdomen and spermathecae with no considerable differences compared to P. spinipes ; apex of postabdomen telescopically retractile; spermathecae distinctly cylindrical, about as long as high in lateral view (a larger series of specimens is needed to verify the consistency of some very slight differences of the outlines of both the 7th tergite and sternite as well as of the spermathecae).

Type material. The holotype ♂ of Pseudorhicnoessa longicerca sp. nov. is labelled “[printed white label] Papua-New-Guinea / Central Prov., / Gaba Gaba, [9°48'12"S 147°30'48"E] / 12.xii.1982 // [printed white label] J.W. Ismay / strand line / NHM 1995-E16 // [printed red label] Holotypus / Pseudorhicnoessa / longicerca sp. nov. ♂ / L. Munari des. 2013”. The holotype is double mounted (micropinned to a block of plastic matter), is in excellent condition (apical tarsomeres of left hind leg lost), with the abdomen removed, dissected, and stored in a small plastic tube filled with glycerol and pinned below the specimen. Paratypes: same data as holotype, 3 ♂♂ 4 ♀♀; Papua New Guinea, Port Moresby, Ela Beach, 6.x.1963, D.K. McAlpine, 4 ♂♂ (formerly misidentified as P. spinipes ). The holotype and five paratypes (2 ♂♂ 3 ♀♀), all from the same type locality, are deposited in the Natural History Museum, London, UK; a pair of paratypes is deposited in the author’s collection together with a third specimen (♂) formerly misidentified as P. spinipes (see above) and already present in the author’s collection; 3 additional males from Ela Beach (Port Moresby, PNG) are also deposited in the Australian Museum, Sydney, Australia.

♀♀ of P. spinipes are at present indistinguishable from those of P. longicerca sp. nov.. Consequently, among the material identified as P. spinipes , preserved in many scientific institutions, there might be occasional specimens of P. longicerca intermixed with Malloch’s species, these two species occurring in sympatry and syntopy, at least in the Papuan localities recorded above.

Distribution. Papua New Guinea.

Etymology. The species epithet, longicerca , is a compound name of Latin and ancient Greek derivations and refers to the remarkably long cerci of the male terminalia.

Remarks. The genus Pseudorhicnoessa includes two vicariant species so far, namely P. rattii Munari, 1981 , distributed throughout the Indian Ocean and well characterized by structures of the male terminalia, and P. spinipes Malloch, 1914 , with a wide distribution in the western Pacific Ocean. As mentioned previously, the new species occurs in sympatry, as well as in syntopy, with the common P. spinipes in the eastern territories of Papua New Guinea. Pseudorhicnoessa longicerca sp. nov. is strikingly similar and likewise very closely related to the very common P. spinipes as to external features, especially chaetotaxy, but is distinguished from the latter (figs 7 – 13) almost exclusively by structures of the external terminalia of male (figs 7 – 9), in particular by having the cercal appendages strongly developed, longer than anterior and posterior surstyli length (figs 7 – 8), with fused subapical part and distinctly bifid apex (fig. 8); in P. spinipes these appendages are simple, short (fig. 12), as usual for the entire subfamily. Additional characters of the external male terminalia, such as the morphology of the anterior and posterior surstyli, are quite consistent, though to a lesser extent (figs 10 – 13). Several male specimens of the allied P. spinipes from northern Queensland ( Australia) (especially from localities facing the south-eastern coast of Papua New Guinea) and from the Couburg Peninsula (Northern Territory, Australia) have also been examined in order to ascertain the possible occurrence of P. longicerca sp. nov. among them. As a result, no specimens of the latter species were found from those northern regions of Australia. Thus, from the present state of knowledge, we can infer that the distribution of the new species might supposedly be strictly localized in the south-eastern coast of Papua New Guinea, or at most on the eastern seashores of that large island. While examining materials of P.

spinipes from the collection of the Australian Museum, Sydney, I was also able to study Malloch’s holotype of Tethina (Macrotethina) tibiseta , which was formerly placed in synonymy under P. spinipes ( Munari, 2002) . On that occasion, the synonymy was based on the examination of three paratypes of T. tibiseta from the collection of the National Museum of Natural History, Smithsonian Institution, Washington D.C.. Thus, I can now corroborate that former synonymy, this time based on Malloch’s holotype.

Figures

FIGURES 7 – 9. ♂ terminalia of Pseudorhicnoessa longicerca sp. nov.. 7: lateral view; 8: posterior view; 9: left anterior surstylus, anterior view. Scale bar = 0.3 mm.