Aphaniosoma gatti, Ebejer, Martin J., 2016

Ebejer, Martin J., 2016, The Moroccan species of Chyromyidae (Diptera) with descriptions of five new species of Aphaniosoma Becker, Zootaxa 4208 (3), pp. 221-236 : 222-224

Aphaniosoma gatti sp. n.

Figs 1–3

Diagnosis. A yellow species with black scutal vittae and transverse bands on abdominal tergites; absent pair of long setae in front of ocellar triangle; well-developed dorsocentral and presutural intra-alar setae, modified hind trochanter in the male.

Description. Male: Head: all yellow except for black ringed ocelli; frons broad but narrowed anteriorly, at level of antennae 0.7 width that at level of anterior ocellus; gena narrow in front, deeper behind, in profile, below middle of eye, about equal to height of eye, with numerous glistening pale yellow setulae; occiput in profile visible behind eye, with pale postocular setulae in one row; mouth parts all yellow; 2 vibrissal setulae moderately developed: longest about equal to orbital seta; face very short, poorly sclerotized and depressed; median carina barely developed; antenna yellow, pedicel with distinct short pale seta dorsally; postpedicel with fine but distinct pubescence along anterior margin shorter than diameter of basal segment of arista; 1st segment of arista and extreme base of second segment yellow, remainder of second segment brown, with fine pubescence; chaetotaxy: 2 strong orbitals, with 4 short orbital setulae in front, postverticals short and convergent; 1 medial vertical and 1 lateral vertical, both strong; anterior pair of ocellars proclinate and as long as hindmost orbital, hind pair, between hind ocelli, erect and about 2/5 length of anterior pair; about 18 very pale short setulae across middle of frons.

Thorax: yellow; scutum with 4 black vittae, middle pair narrowly separated, ending anterior to hindmost dorsocentral setae, lateral vitta reaching level of hind dorsocentral; vittae appear grey owing to dense yellowish pollinosity of whole scutum; scutellum clear yellow except for narrow brown line along infero-lateral margin at base; metanotum black; pleura yellow with pale brown on middle of anepisternum and katepisternum, black on meron; chaetotaxy: 2 postpronotals, 1 strong incurved internal post-postpronotal, 1 long presutural, 2 notopleural, 1+2-6 intra-alars the postsutural often in two rows, 1 postalar, 1+3 dorsocentrals and two setulae anterior to first seta, 2+5 acrostichals with prescutellars more developed, 4 scutellars, 1 anepisternal with 4 setulae below it, 1 katepisternal at upper posterior corner with 5 setulae vertically down middle of sclerite.

Wing: veins all pale yellow; distance on costa between R2+3 and R4+5 about 0.6 that between R4+5 and M; distance between cross veins about 1.2 length of posterior cross vein, which is hardly oblique and is about 0.4 length of apical section of vein Cu. Haltere pale yellow.

Legs: modified with thicker front femora having long anterodorsal setae; all legs yellow with numerous scattered pale setulae with those on front tarsomeres longer especially middle setulae being longer than tarsomere 5; apico-ventral seta on mid tibia present; claws black, pulvilli normal; 5th tarsomere of all legs yellow; hind trochanter ( Fig. 3 ) modified with only a barely discernible antero-ventral ridge bearing very fine setulae.

Abdomen: basal 4 tergites yellow with dark brown transverse bands dorsally, broader at middle than at sides; tergite 5 enlarged, markedly more setulose than preceding tergites; abdominal setulae pale brown.

Postabdomen ( Figs. 1, 2 ): sternite 5 with lateral ventral projections, epandrium small and pale, bearing a dark brown spot dorsally on each side and elongated surstylus, cerci small and pale, hypandrium distinct, pregonite not discernible, phallapodeme with long antero-dorsal process, postgonites not discernible, distiphallus not discernible, presumably very short, translucent membranous.

Female: similar to male apart from secondary sexual characters.

Body length: male 1.8 mm, female 2 mm, Wing length: male 1.8 mm, female 2.1 mm.

Variation. Both sexes vary somewhat in the extent of brown or black marks on the pleura. The number of setae and the regularity of their rows on the scutum is also variable.

Etymology. This species is named in honour of my long-standing friend and colleague Dr Paul Gatt who is also the person to have collected this species.

Material. Holotype: male, El-Jadida , Azemmour beach & dunes, 11.vi.2005, PG (registration number: NHMUK 010579825 ;) . Paratypes: 2♂ 2♀, same data and depository ; 1♂1♀ in MJE collection; 1♂ 1♀ in the Institute of Science, Rabat, Morocco .

Similar species. The new species belongs to the A. collini group, distinguished by long dorsocentral setae and a well-developed presutural intra-alar as well as males having modified hind trochanters. It differs from congeners in the structure of the male postabdomen mainly in sternites 5 and 6 and the shape of the surstylus, and in the shape of the hind trochanter.

Figures

FIGURES 1 – 3. Aphaniosoma gatti sp. n. 1) postabdomen lateral, 2) pregenital sternites: a, sternite 5 lateral; b, sternite 6 lateral; c, sternite 5 ventral, 3) base of hind leg posterior aspect, a = male, b = female. Abbreviations: ph apd = phallapodeme, tg 6 = tergite 6, ep = epandrium, cerc = cercus, st 6 = sternite 6, hyp = hypandrium, st 5 = sternite 5, ph = phallus, surs = surstylus. Scale bar = 0.15 mm.