Ceratomerus athertonius, Bradley J Sinclair, 2003

Bradley J Sinclair, 2003, Taxonomy, Phylogeny and Zoogeography of the Subfamily Ceratomerinae of Australia (Diptera: Empidoidea), Records of the Australian Museum 55, pp. 1-44 : 9-10

Ceratomerus athertonius n.sp.

Figs. 1, 2, 9–11, 17, 18, 28, 124

Type material. HOLOTYPE 3, “ AUST: N.QLD[Northern Queensland] 31.6 km up Mt. Lewis Rd., 1000 m / 16.iv.1994, cascading/ creek, B.J. Sinclair / 16°36'S 145°16'E ”; “ HOLOTYPE / Ceratomerus / athertonius / Sinclair [red label]” AMS K175239 . P ARATYPES: Queensland: 233, 8♀♀, same data as holotype ( AMS, CNC); 3♀♀, same locality as holotype, 21–22.iv.1994 ( ZFMK); 2 33, 3♀♀, 4 km up Mt. Edith Rd, 800 m, Danbulla SF, 17°05'S 145°33'E, Ck, 22.iv.1994, BJS; 2.4 km up Mt. Edith Rd, 700 m, Danbulla SF, 27.iv.1994, 17°05'S 145°33'E, sandy str., BJS ( AMS); 233, 11♀♀, 4 km up Mt. Edith Rd , 800 m, Danbulla SF, 17°05'S 145°33'E, MT across Ck, 22–27.iv.1994, BJS ( ANIC, AMS, CNC); 3♀♀, Mt. Edith , 4–7 m off Danbulla Rd, 27.iv.1967, DHC ( ANIC).

Diagnosis. Males readily recognized by the highly modified midlegs and long spatulate processes projecting from the anal lobe of the wing. Females are separated by lacking acrostichals, dark stylus, and pale to dark coloured pleura with at least the laterotergite and meron darkened.

Description. Wing length 3.2–3.4 mm.

Male. Head dark brown, face with white pruinescence, lacking setulae; ocellar triangle with 2 long, divergent bristles, inserted between ocelli; postocellar bristle short, one-half length of ocellar bristle; 3 pairs of long vertical bristles, shorter than ocellar bristles; postocular bristles very short, slender, overlapping less than one-fifth of eye. Antenna long, with scape subequal to height of eye; pedicel oval with posterior fringe of setae; scape sparsely covered by setulae, with 2 long, dorsal setae and 1 long, ventral seta. Postpedicel 1.3× longer than scape, covered by long, dense pruinescence, basal half rectangular; apical half strongly differentiated from base, tapered to short threesegmented stylus, one-third length of postpedicel; segment 8 not longer than wide; stylus concolorous with remaining antenna. Base of labrum lacking dorsal process; palpus yellow, long and slender, one-fourth length of labrum, with lateral row of short, dark setae and stout, subapical seta; prementum with short setae only.

Thorax. Mesonotum, postnotum, laterotergite, and meron dark; remaining pleura, lateral margin of scutum, postpronotal lobe, and postalar yellowish-brown. Acrostichals absent; 4 dc, first and fourth bristles short and slender; 1 pprn; 1 presut spal; 1 npl; 2 psut spal, upper short and slender; 1 slender, short pal; 2 sctl; numerous setulae scattered on scutum, particularly among dc. Antepronotum with 2 long, lateral setae.

Wing ( Fig. 9). Posterior margin with strongly sclerotized, triangular prolongation, lined with long setulae; projection bearing 3 long, narrow processes, with dilated or spatulate tips ( Fig. 11); wing stem with long, stout setae. Stigma at apex of cell r 1 broad, dark, remainder of wing infuscate; single long costal seta; costal margin with unmodified setulae. R 4+5 acutely forked; auxiliary crossvein between R 2+3 and R 4 lacking; cell dm trapezoidal; medial fork petiolate, proximal to radial fork by slightly less than length of R 4. Halter with dark knob and white shaft.

Legs. Coxae yellow, concolorous with pleura; fore femur yellow, apex of mid and hind femur dark; tibiae with yellow dorsal margin; remaining segments dark. Fore coxa more than twice length of mid and hind coxae combined; apical third concave with inner tuft of stout setae and pair of long, wavy, sclerotized processes. Fore trochanter not lengthened, bearing row of 3–4 long, inner setae. Fore femur with pv row of very long, stout setae, more than twice width of femur; basal half with 5 widely spaced av setae, basal seta projecting obliquely; mid-length with irregular row of long anterior setae, becoming more stout apically. Fore tibia shorter than femur, apex not dilated with anteroapical comb; pv margin with row of long erect setae, length nearly twice width of tibia. First tarsomere slightly shorter than fore tibia, with 2 long ventrobasal setae; distal 4 tarsomeres longer than first tarsomere; fifth tarsomere dorsoventrally flattened.

Mid coxa with stout anterior seta. Basal two-thirds of mid femur strongly swollen, with pv tooth; av and pv margins with long stout setae, less than basal width of femur; basal third with anterior, spine-like seta; apical third of femur narrow, with long anterior setae ( Fig. 1). Mid tibia shorter than femur, with concave ventral margin; apical half expanded; pv margin with row of stout setae, slightly longer than width of tibia, and short basal hooked process; base with long projecting lobe, base of lobe surrounded by series of short, convoluted lobes ( Fig. 2). First tarsomere thin, longer than femur and tibia combined; apex with pair of ventral bristles; fifth tarsomere somewhat flattened.

Hind coxa bearing unmodified setae. Hind femur less than twice length of fore femur; base with pv oval zone, devoid of setae, with fringe of 7 long setae; mid-length with row of slender, ventral setae; lacking preapical dorsal bristle. Hind tibia longer than femur, apex dilated, bearing posteroapical comb; 4 ad bristles and 2 dorsal bristles on apical half. Hind tarsomeres longer than tibia; first tarsomere with 1 erect, ventral seta near base; pv margin with erect setae.

Abdomen. T1 pale brown; T2–6 dark brown, with long slender setae, especially on posterior margin; S1–6 yellow; T7 light brown, posterior margin membranous, lacking long posterior setae; S7 slightly longer than preceding sternite, anterolateral margin produced anteriorly, fused to S8; T8 onefifth length of sternite, expanded laterally bearing long setae.

Terminalia ( Fig. 17). Hypandrium with posterior flaplike process; paired articulated, curved postgonites projecting obliquely near apex of phallus. Apex of phallus with pair of sickle-shaped appendages arching posteriorly between postgonites. Epandrium with 1 very long stout seta on ventrolateral margin; epandrial lobe long, tapered, bearing 4 broad, peg-like lateral setae. Bacilliform sclerite broad, separate from epandrium. Surstylus short, round, projected posteriorly, little longer than wide, bearing marginal setulae. Cercus short, fleshy, apex acute, expanded laterally around anus; posterior surface well sclerotized.

Female. Similar to male except as follows: postpedicel slightly longer than scape; segment 8 1.5× longer than wide; palpus brown; mesonotal bristles long and stout; occasionally pleura entirely brown; wing ( Fig. 10) lacking posterior projection and appendages, venation unmodified; cell dm rectangular; medial fork with short petiole, basal to radial fork by nearly length of R 4. Legs lacking modified appendages and setae; apex of fore tibia not expanded. Mid tibia with 1 long ventral, 1 ad and 1 pd apical bristle; 1 ventral and 1 ad bristle at mid-length; basal third with 1 ad and 1 pd bristle. Apical segments retracted into segment 7; posterior margin of T7 with narrow, yellowish-brown extension, bearing posterior fringe of setae; lateral margin of S7 straight. Terminalia ( Fig. 18): posterior margin of T8 membranous, with dense fringe of long setae along lateral margin; pair of flat lateral sclerites extend into segment 7 from anterior margin of T8; S8 with ventral setulae; posterior margin invaginated, forming internal plate. T10 split medially into pair of rectangular sclerites, bearing double row of spine-like setae along posterior margin. Cercus bearing row of similar setae, with short, slender marginal setae. Spermathecal receptacle oval, with short, wide neck.

Distribution. This species is known only from the Atherton Tableland and Mt. Lewis of northern Queensland from 800 to at least 1000 m ( Figs. 28, 124).

Etymology. Named in reference to the Atherton Tablelands where the first specimens of this species were taken by Dr D.H. Colless.