Dasyrhicnoessa macalpinei, Munari, 2004

Munari, L., 2004, Beach Flies (Diptera: Tethinidae: Tethininae) From Australia and Papua New Guinea, with Descriptions of Two New Genera and Ten New Species, Records of the Australian Museum 56 (1), pp. 29-56 : 40

Dasyrhicnoessa macalpinei n.sp.

Figs. 13–14

Type material. HOLOTYPE 3 Australia, Northern Territory “NT: Buffalo Ck, / Darwin; 2–5 Mar. / 1996; D.K. McAlpine, / G. R. Brown // HOLOTYPUS / Dasyrhicnoessa / mcalpinei sp.n. 3 / L. Munari des.” AM K186739 . The specimen is in relatively good condition: the left fore tibia and tarsus are missing, and the head is glued near the specimen. The holotype is deposited in AM, and is double mounted (glued on the tip of a triangular card label); abdomen dissected, stored in glycerol in a small plastic tube, and pinned below the specimen.

Description. Size. Body length 1.3 mm, wing length 1.3 mm, wing width 0.5 mm. Habitus. Small fly with body and legs pale yellowish. Setal vestiture pale yellow to dark brownish. Wings yellowish grey. Head. Yellowish to greyish yellow; frontal and orbital vittae pale yellow, distinctly paler than rest of frons; ocellar triangle and occiput greyish; golden yellow patch on both sides of ocellar triangle; paravertical setae thin, strongly inclinate; inner vertical seta inwardly curved, strong, about as long as lateroclinate outer vertical seta; postocular and postgenal setae very short, thin, former setae in 1–2 irregular rows; upper postocular seta long, inclinate towards inner vertical seta; ocellar triangle bearing pair of moderately long, thin pseudopostocellar setae in addition to pair of strong ocellars; a few very short, thin setulae between ocellars and pseudopostocellars, and behind latter setae; 3 strong, lateroclinate orbital setae intermixed with sparse, thin, short setulae; 3 pairs of frontal setae intercalated with 3 pairs of short, thin setulae, all setae and setulae inclinate; antennal postpedicel bearing brownish, short-haired arista; eye micropubescent, very large, slightly oblique, subrectangular, its longest diameter 5.5× as long as genal height; 5 brownish to black peristomal setae, two anterior ones, including vibrissa, long and strong; mouth parts pale yellow, with labellum stumpy, shorter than length of buccal cavity, and palpus long, slender, bearing scattered black setulae. Thorax. Yellowish; 1+3 dorsocentral setae; acrostichal setulae in 4 irregular rows; prescutellar acrostichals long; postpronotal lobe bearing 3 setae (only two are discernible in holotype, lower seta being missing), each with different inclination, posterior seta long and strong, anterior setae shorter and weaker; 1 long presutural seta; 2 notopleurals, anterior one slightly longer; 1 supra-alar (missing in holotype), below it 1 shorter and weaker seta; 2 postalars, external one distinctly longer and stronger; scutellum with 4 long marginal setae; both proepisternal and proepimeral setae present; anepisternum with scattered setulae, bearing 3 long, posteriorly directed, posteromarginal setae, mid one distinctly longer and stronger, and 1 erect seta at posterodorsal margin; katepisternum with few scattered setulae, bearing long and strong posterodorsal seta; anepimeron, katatergite, and meron without setae and setulae. Legs. Evenly setulose, bearing short brownish to blackish setae and setulae, except for foreleg having coxa with scattered, pale brownish, long setae, and femur with posterodorsal and posteroventral rows of spaced, long setae; hind tibia with long, posteroventral pubescence on distal half, formed by several, erect, yellowish setae; fore femur without true ctenidium, only with row of short, thin setulae anteroventrally on distal half; mid femur with comb of 6 spine-like, short, subequal in length, posteroventral black setae on distal half; all legs, including coxae, yellow; last tarsomere slightly infuscate. Wing. Veins yellowish, membrane yellowish grey; alula with fringe formed by erect, blackish setae; costal vein reaching end of M 1, bearing several, spaced, microscopic setulae on both dorsal and ventral surfaces; R 2+3 distinctly bisinuate, diverging from R 4+5 distally; R 4+5 and M 1 parallel; crossvein r-m ending just before middle of cell dm; crossvein dm-cu distinctly shorter than half of last section of CuA 1; halter yellow. Abdomen. Yellowish brown, with setal vestiture formed by golden brown setae and setulae; transverse stripes at posterior edge of tergites yellowish. Male terminalia ( Figs. 13–14). Epandrium bearing characteristic cluster of long, strong setae on entire anteroventral surface, in particular on anterior part, and short setae on all remaining posterior surface; cercus long and narrow, pointed apically, pubescent, dorsally covered with microscopic hairs and with long setae; anterior surstylus strongly reduced, rounded at apex, bearing scattered, thin setae; posterior surstylus subrectangular in lateral view, long, straight, and narrow in posterior view, bearing numerous short setae and cluster of short, stout tubercles on distal third; aedeagal apodeme long and straight, without evident sinuosity; ejaculatory apodeme diaphanous, poorly sclerotized, with distal fan well developed; distiphallus long, slender, ribbon-like, distinctly pointed at apex, bearing several, scattered, microscopic hairs.

Female. Unknown.

Distribution. Australia (NT).

Remarks. As regards the external morphology, the new species is particularly characterized by having the hind tibia of the male bearing long, thin, yellowish pubescence on the posteroventral distal half. Personally, I have never observed this character in any other Dasyrhicnoessa species. It would be interesting to know whether the females also share such a peculiar feature.

Etymology. The new species is gratefully named after Dr David K. McAlpine who collected the holotype and facilitated my study of a large number of specimens held at the Australian Museum.