Dasyrhicnoessa malayana, 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 : 284-288

Dasyrhicnoessa malayana sp. nov.

( Figs 3–4 )

Diagnosis. This species is distinguished from congeners mainly by the following combination of characters: body length 2.28 mm, wing length 1.95 mm; vertex and occiput of head brown to black; ocellar triangle blackish; frons bronze brown, excepting a yellowish brown sector surrounding the ptilinal fissure; gena with a very narrow, dull brown, longitudinal stripe; antenna brown (scape and pedicel) to dark brown (basal flagellomere); vertical diameter of eye about 7.3 times as long as genal height; mouthparts dark brown; postpronotal lobe and tip of scutellum yellow; acrostichal setulae arranged in 5 – 6 irregular rows; fore- and hind femora only slightly swollen; anteroventral ctenidial comb of forefemur with 7 – 9 minute, strong spinulae; posteroventral armature of male mid femur formed by a long row of slightly curved, acutely pointed, strong setae decreasing in length towards apex of femur; hind basitarsomere with antero- and posteroventral combs of very close, short, black spinulae; crossvein dm-cu more than one third of the length of last section of CuA1; abdomen with velvety black spot on each side of tergites 3 – 5; male terminalia with epandrium large, strongly setose, bearing an obvious, transverse thickening ventrally; anterior surstylus beak-like, roughly subtriangular in lateral view; posterior surstylus, in lateral view, truncated apically and curved forward, bearing several stout spinulae on ventral side.

Description. Size. Body length 2.28 mm, wing length 1.95 mm.

Habitus. Small fly, with dark brown body and yellow legs; abdomen with velvety black spots on the sides of tergites; setal vestiture black; wing greyish.

Head. Higher than long; vertex and occiput brown to black; frons bronze brown, excepting a yellowish brown sector surrounding the ptilinal fissure; face, clypeus, and gena yellowish brown, the latter with a very narrow, dull brown, longitudinal stripe; postocellar setae strongly convergent; medial vertical seta slightly longer than lateral seta; several pale postocular setae arranged in 2 or more irregular rows, dorsal postocular seta strong, inclinate; ocellar triangle blackish, bearing a few minute setulae in addition to the usual long ocellars; 3 long fronto-orbital setae, mid one strongly lateroclinate, intermixed with small setulae; a row of minute, inclinate setulae arranged on medial side of fronto-orbital plate; 3 pairs of inclinate interfrontal setae, 2 anterior pairs more or less cruciate at apex; some minute, additional setulae between interfrontal setae; antenna brown (scape and pedicel) to dark brown (basal flagellomere); arista blackish, microscopically pubescent; eye very large, vertically oblong, densely micropubescent, bearing a multitude of interfacetal ommatrichia, its vertical diameter about 7.3 times as long as genal height; 7 peristomal setae, 3 anteriors, including true vibrissa, increasingly stronger and longer towards vibrissal angle; clypeus narrow; mouthparts dark brown, with labellum distinctly shorter than buccal cavity length.

Thorax. Brown, with a longitudinal, blackish band on middle of mesonotum, becoming broader in the prescutellar area; postpronotal lobe and tip of scutellum yellow; 1+3 dorsocentral setae; acrostichal setulae arranged in 5 – 6 irregular rows; acrostichal prescutellar setae very long; 3 postpronotal setae intermixed with some tiny setulae, each major seta with different orientation; 1 very long presutural; 2 notopleurals; 1 supra-alar; 2 postalars; several rows of setulae between dorsocentrals and the lateral side of scutum; scutellum with 2 pairs of strong setae; 1 proepisternal; 1 proepimeral; anepisternum sparsely setulose, with 2 – 3 postero-marginal setae and 1 dorsally oriented, posterodorsal seta; katepisternum sparsely setulose, with 1 seta on posterodorsal margin; anepimeron and meron without setae and setulae. Legs. Mostly yellow, with 2 apical tarsomeres dark brown; forecoxa with many long setae, mid and hind coxae each with a long seta, hind trochanter with a long ventral seta; fore- and hind femora only slightly swollen; forefemur with a row of long posterodorsal and posteroventral setae; anteroventral ctenidial comb of forefemur with 7 – 9 minute, strong spinulae; foretibia and foretarsus evenly short setulose; posteroventral armature of male mid femur formed by a long row of slightly curved, acutely pointed, strong setae decreasing in length towards apex of femur; mid tibia and tarsus evenly setulose, except for an apicoventral spur on mid tibia; hind femur with a long row of thin setae postero- and anteroventrally; hind tibia and tarsus evenly setulose, except for an apicoventral spur on hind tibia; hind basitarsomere with antero- and posteroventral combs of very close, short, black spinulae. Wing. Veins brownish yellow, membrane pale grey; alula as usual for the genus; subcostal break with obvious notch; costal vein extending barely beyond end of R4+5, giving the misleading impression of reaching end of M1; R2+3 and R4+5 rather divergent distally; R4+5 and M1 subparallel in distal half; crossvein r-m ending before middle of cell dm; crossvein dm-cu more than one third of the length of last section of CuA1; halter brownish.

Abdomen. Brown, bearing several setulae and fairly long postero-marginal setae; tergites with obvious posteromarginal yellowish stripes; each side of tergites 3 – 5 with obvious velvety black spot. Male terminalia. Epandrium large, strongly setose, bearing an obvious, transverse thickening ventrally; anterior surstylus beak-like, roughly subtriangular in lateral view; posterior surstylus, in lateral view, truncated apically and curved forward, bearing several stout spinulae on ventral side; cercus of normal shape; phallus ribbon-like, unusually broad (lacerated apically), bearing several microtrichia on its surface; ejaculatory apodeme and phallapodeme as usual for the subfamily.

Female. Unknown.

Type material. The holotype ♂ of Dasyrhicnoessa malayana sp. nov. is labelled “[beige label] [printed] Malay Penin: / [handwritten] Negeri Sembilan / Port Dickson [2°31′N 101°48′E] / 17.2. [printed] 193 [handwritten] 3: // [printed white label] Ex F.M.S. / Museum. / B.M. 1955-354. // [printed red label] Holotypus / Dasyrhicnoessa / malayana sp. nov. ♂ / L. Munari des. 2013”. The holotype is double mounted (micropinned to a block of vegetable matter), is in excellent condition (right hind leg lost), with the abdomen removed, dissected, and stored in a small plastic tube filled with glycerol and pinned below the specimen. The holotype is deposited in the Natural History Museum, London, UK.

Distribution. Malaysia (Negeri Sembilan).

Etymology. The species epithet, malayana , refers to the country in the Malay Peninsula where the holotype was collected.

Remarks. The new species belongs to the Dasyrhicnoessa tripunctata -group, which is characterized mainly by an obvious velvety black spot on each side of tergites 3 – 5, sometimes also present dorsally, and by a large posterior surstylus. The shape of the anterior and posterior surstyli is very distinctive and is important to correctly identify this species. In addition to the new species described here, this species-group comprises the following other taxa: D. adelpha Munari, 2005 , India ( Goa); D. celata Munari, 2010 , Bismarck Islands; D. tripunctata Sasakawa, 1974 , widely distributed throughout the western Pacific coasts. The species of this group are rather similar externally and examination of the male terminalia morphology is needed to accurately identify them. Finally, it should be stressed that the dark colour of the new species might be due to a very slight greasy layer covering the head and thorax.

Dasyrhicnoessa paradoxa sp. nov. ( Figs 5–6 )

Diagnosis. This species is distinguished from congeners mainly by the following combination of characters: body length 1.91 – 2.06 mm, wing length 1.58 – 1.80 mm; tiny and delicate fly, with pale grey setal vestiture; fronto-orbital plate of head distinctly pale brownish; vertical diameter of eye about 8 times as long as genal height; acrostichal setulae arranged in 4 – 5 irregular rows; legs with apical tarsomeres very faintly infuscate; fore- and hind femora distinctly swollen; anteroventral ctenidial comb of forefemur virtually lacking, only five spaced, thin setulae present; posteroventral armature of male mid femur strongly weakened, with a row of remarkably spaced, thin, pale setae on entire length; hind femur with a long, posteroventral row of pale setae; crossvein dm-cu less than one third of the length of last section of CuA1; male terminalia with anterior surstylus small, rod-like; posterior surstylus deeply bilobate, with a posterior, long, straight, rod-like process, which looks firmly connected to the epandrium, and an anterior process distinctly subrectangular, bearing strikingly long, sinuous setae on both dorsal and ventral sides.

Description. Size. Body length 1.91 – 2.06 mm, wing length 1.58 – 1.80 mm.

Habitus. Tiny, delicate fly, with pale brown body and yellow legs; setal vestiture appearing slightly diaphanous, pale grey; wing pale grey.

Head. Slightly higher than long; vertex and occiput brown to grey, frons yellow, fronto-orbital plate distinctly pale brownish, face yellow medially, remarkably depressed, mostly membranous, gena narrow, yellow, with a very faintly translucent, narrow, longitudinal stripe; postocellar setae inclinate as well as slightly proclinate; medial vertical seta lost in the holotype; lateral vertical seta long, very slightly lateroclinate; postocular setae arranged in 2 distinct rows, dorsal postocular seta strong, inclinate; ocellar triangle grey microtomentose, bearing a few minute setulae in addition to the usual long ocellars; 3 long, lateroclinate, fronto-orbital setae intermixed with some inclinate, small setulae; 3 pairs of inclinate interfrontal setae, 2 anterior pairs cruciate at apex, no additional setulae between them; antenna mostly yellow, with basal flagellomere faintly infuscate on dorsal half; arista black to dark grey, microscopically pubescent; eye very large, vertically oblong, densely micropubescent, bearing a multitude of interfacetal ommatrichia, its vertical diameter about 8 times as long as genal height; 4 – 5 peristomal setae, including true vibrissa, increasingly longer towards vibrissal angle; clypeus narrow, partly concealed below ventral part of face; mouthparts pale yellow, with labellum as long as or slightly shorter than buccal cavity length.

Thorax. Greyish brown, except for postpronotum and apex of scutellum, which are yellow; 1+3 pale grey dorsocentral setae; acrostichal setulae arranged in 4 – 5 irregular rows; acrostichal prescutellar setae long; 3 postpronotal setae intermixed with 2 – 3 tiny setulae, each major seta with different orientation; 1 presutural; 2 notopleurals; 1 supra-alar; 2 postalars; 1 – 2 rows of short setulae between dorsocentrals and the lateral side of scutum; scutellum with 2 pairs of setae (lost in holotype); 1 proepisternal; 1 proepimeral; anepisternum sparsely setulose, with 3 postero-marginal setae and 1 dorsally oriented, posterodorsal seta; katepisternum sparsely setulose, with 1 seta on posterodorsal margin; anepimeron and meron without setae and setulae. Legs. Mostly yellow, with apical tarsomeres very faintly infuscate; forecoxa with some fine setae in addition to 2 long, black setae, mid and hind coxae each with 1 long seta; fore- and hind femora distinctly swollen; forefemur with some pale setae dorsally and 6 posterior to posteroventral, longer, stronger setae; anteroventral ctenidial comb of forefemur virtually lacking, only five spaced, thin setulae present; foretibia and foretarsus evenly short setulose; posteroventral armature of male mid femur strongly weakened, with a row of remarkably spaced, thin, pale setae on entire length; mid tibia and tarsus evenly setulose, except for an apicoventral spur on mid tibia; hind femur with a long, posteroventral row of pale setae; hind tibia and tarsus evenly setulose, except for an apicoventral spur on hind tibia. Wing. Veins brownish yellow, membrane pale grey; alula small; subcostal break with obvious notch; costal vein extending barely beyond end of R4+5, giving the misleading impression of reaching end of M1; R2+3 and R4+5 rather divergent distally; R4+5 and M1 subparallel on distal half; crossvein r-m ending before middle of cell dm; crossvein dm-cu less than one third of the length of last section of CuA1; halter whitish.

Abdomen. Brown, bearing several setulae and fairly long postero-marginal setae; 4th–6th tergites each with obvious postero-marginal yellowish stripe. Male terminalia. Epandrium large, bearing a few scattered, long setae; anterior surstylus small, rod-like, with sinuous profile, bearing some thin setae apically; posterior surstylus deeply bilobate, with a posterior, long, straight, rod-like process, which looks firmly connected to epandrium, and an anterior process distinctly subrectangular, bearing strikingly long, sinuous setae on both external and ventral sides; cercus narrow, with a few moderately long setae; phallus ribbon-like, basally strongly setulose on ventral surface, remaining surface towards apex bearing sparse, small setulae dorsally; ejaculatory apodeme and phallapodeme as usual for the subfamily. Female terminalia. Apex of postabdomen telescopically retractile; cercus small, finely pubescent; spermathecae not examined.

Type material. The holotype ♂ of Dasyrhicnoessa paradoxa sp. nov. is labelled “[handwritten white label] Malaysia / Selangor. Port / Kelang. [3°0′0″ N 101°24′ 0″E] saltmarsh / 4.iii.1982. C.E. Dyte // [no label with BM accession number] // [printed red label] Holotypus / Dasyrhicnoessa / paradoxa sp. nov. ♂ / L. Munari des. 2013”. The holotype is double mounted (micropinned to a block of plastic matter), is in fairly good condition (some major mesonotal setae and right mid leg lost), with the abdomen removed, dissected, and stored in a small plastic tube filled with glycerol and pinned below the specimen. Paratypes: 2 ♀♀, same data as holotype. Both the holotype and one paratype are deposited in the Natural History Museum, London, UK, the second paratype is deposited in the author’s collection.

Distribution. Malaysia (Selangor).

Etymology. The species epithet, paradoxa , is of ancient Greek derivation and refers to the very peculiar shape of the male terminalia.

Remarks. A set of characters distinguishes this new species unequivocally, segregating it from all other congeners. The most important feature is the shape of the posterior surstylus, which is deeply bilobate, with a posterior, long, straight, rod-like process, which looks firmly connected to the epandrium, and a distinctly subrectangular anterior process, bearing strikingly long, sinuous setae on both external and ventral sides. These remarkably long setae recall fairly well those present on the posterior surstylus of Dasyrhicnoessa platypes Sasakawa, 1986 from the Ryukyu Islands ( Japan), although the long setae of Sasakawa’s species are not sinuous ( Sasakawa, 1986: 438, fig. 3). Additional major characters that distinguish D. paradoxa from congeners are: the pale grey setal vestiture of the body; fronto-orbital plate of head distinctly pale brownish; anteroventral ctenidial comb of forefemur virtually lacking (only five spaced, thin setulae present); posteroventral armature of male mid femur strongly weakened, with a row of remarkably spaced, thin, pale setae on entire length; hind femur with a long, posteroventral row of pale setae.

Figures

FIGURES 3 – 4. ♂ terminalia of Dasyrhicnoessa malayana sp. nov.. 3: lateral view; 4: posterior view. Scale bar = 0.1 mm.

FIGURES 5 – 6. ♂ terminalia of Dasyrhicnoessa paradoxa sp. nov.. 5: lateral view; 6: posterior view. Scale bar = 0.1 mm.