Aphaniosoma nitidum, 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 : 227-228

Aphaniosoma nitidum sp. n.

Figs 7–8

Diagnosis. A lustrous black species with pearly white scutellum and notopleuron, completely pale yellow legs, absent pair of long frontal setae in front of ocellar triangle; antenna yellow in the male, black in the female.

Description. Male: Head: all yellow except for black ocellar triangle and occiput; frons as broad as long, narrowed anteriorly, at level of antennae 0.5 width that at level of anterior ocellus; gena narrow in front, deeper behind, in profile, below middle of eye, about equal to 0.2 height of round eye, with numerous white setulae; occiput in profile barely visible behind eye, with postocular setulae irregularly in one row, black dorsally and yellow ventrally; mouth parts all yellow; 1 short vibrissal setula poorly differentiated from buccal row of setulae; face short and narrow, depressed and poorly sclerotized; median carina very narrow and visible only below lunule between antennal bases; antenna yellow, pedicel with distinct short seta dorsally; postpedicel with fine pubescence along anterior margin shorter than diameter of basal segment of arista; 1st segment of arista yellow only at base, otherwise brown as second segment, with fine pubescence; chaetotaxy: 2 orbitals as long as ocellar triangle and black proclinate ocellars, with 2 short ors setulae in front, postverticals short and crossed; 1 medial vertical and 1 lateral vertical, both strong; about 12 short yellow setulae across middle of frons, all of uniform length.

Thorax: black appearing lustrous even though there is a thin microscopic greyish pollinosity especially on pleura; notopleural lobe and scutellum pearly white except at margin around base of basal scutellar seta; metanotum black; pleura black with pale yellow dorsal margin of katepisternum; chaetotaxy: 1 postpronotal, incurved internal post-postpronotal not discernable, 1 presutural, 2 notopleural, 0+6 intra-alar, 1 postalar, 2+5 dorsocentrals, only prescutellar strong, 6 acrostichals with prescutellars not developed, 4 scutellars, 1 anepisternal, 1 katepisternal at upper posterior corner with short pale setula in front.

Wing: veins all pale brown except at extreme wing base where all root veins are 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 lies only slightly oblique and is about 0.25 length of apical section of vein Cu. Haltere creamy white.

Legs: yellow, not modified except for slightly thicker femora; numerous pale setulae scattered on all pairs of legs, in addition longer setulae present on fore femur; apico-ventral seta on mid tibia present; claws black in apical half, short, about half length of tarsomere, pulvilli normal; hind trochanter not modified.

Abdomen: tergites black with very narrow yellow hind margins and with relatively long black setae on sides of tergites, especially towards apex of abdomen.

Postabdomen Figs 7–8 : epandrium small and pale, bearing large tri-lobed surstylus, cerci small and very pale, hypandrium distinct bearing a translucent long pregonite, phallapodeme of heavy build, postgonites short not projecting beyond posterior border of epandrium; distiphallus short and membranous.

Female: similar to male but antenna all black.

Body length: male 1.2 mm, female 1.4 mm, Wing length: male 1.4 mm, female 1.5 mm.

Variation. The dark lateral borders of the scutellum may join across the base of the sclerite, one female has a dark mark across the anterior part of the frons.

Etymology. The species epithet refers to the lustrous thorax

Material. Holotype: male, Errachidia, Erfoud, 30 km N, 31°40.108ʹN 04°11.471ʹʹW, 894 m, 1.v.2012, Ziz River , MJE (registration number: NHMUK 010579835 ) . Paratypes: 2♂♂ 2♀, same data and depository.

Similar species. A. nitididorsum Ebejer, 2006 , A. nitidum and an undescribed species from the Middle East form a distinct subgroup within Aphaniosoma . They are not separable on external characters. The characters they share include the lustrous thorax, pearly white scutellum and propensity for females to have a dark pattern on the frons. They also have a heavily built phallapodeme with large lateral flanges and a large peculiar surstylus. The new species differs from A. nitididorsum primarily in the very short lobes of the surstylus and the shape of the pregenital sternites. The species from the Middle East requires further study as specimens originate from three countries. These may ultimately show a clinal variation that includes the Moroccan species.

Figures

FIGURES 7 – 8. Aphaniosoma nitidum sp. n. 7) postabdomen lateral, 8) a = pregenital sternites, ventral; b = base of phallic complex, dorsal. Abbreviations: ph apd = phallapodeme, prg = pregonite, psg = postgonite, tg 6 = tergite 6, ep = epandrium, cerc = cercus, st 5 = sternite 5, st 6 = sternite 6, hyp = hypandrium, basiph = basiphallus, surs = surstylus. Scale bar = 0.15 mm.