Coenosia macrotriseta, Muller & Miller, 2013

Muller, Burgert S. & Miller, Raymond M., 2013, Rediscovering the old from new: two curious species of Coenosia Meigen (Diptera: Muscidae) from South Africa, African Invertebrates 54 (2), pp. 595-595 : 596-599

Coenosia macrotriseta sp. n.

Figs 1A , 2A, 3A , 4 , 5 , 6A, 7A, 8A, 9A

Etymology: From Greek macro (large, long), Latin tri (three) and Latin seta (bristle), which refers to the presence of two pairs of frontal setae and one pair of orbital setae that are greatly enlarged and have globular apexes.

Diagnosis: A grey fly with very striking, apically globular, 2 nd and 4 th pairs of frontal and 1 st pair of orbital setae. The frontal plate and parafrontalia of the head are silver-white-dusted.The 1+3 (with the exception of the most posterior pair) dorsocentral setae are reduced, making them difficult to distinguish from the preceding and surrounding setulae. The trochanters are dark amber in colour.

Description:

Male.

Measurements (mm): ♂ length: 2.92, wing: 2.95; ratios (length/width): head 0.8, thorax 1.4, abdomen 1.6.

Head ( Fig. 2A ): Dichoptic. Eyes bare and somewhat reduced taking up a little more than ⅔ of head when viewed laterally. Antennal scape with two weak setulae, pedicel with one strong setula and one weak setula, and postpedicel not reaching past bottom third of eye; ca 2× length of pedicel. Arista located dorsally on postpedicel, with fine hairs never longer than half the diameter of aristal base, and only present on basal ⅔. Palpus with slight apical dilation, no more than twice the palpal base width ( Fig. 3A ). Gena wide, with face projecting forwards. Head grey-dusted throughout, with exception of silver-white-dusted frontal plate and parafrontalia. One pair of ocellar setae. Four pairs of frontal setae, 1 st and 3 rd pairs undifferentiated, 0.25× as long as 2 nd and 4 th pairs, which are very strongly developed and apically globular with vertical ridges ( Fig. 4A ). Two pairs of orbital setae, the first 1.3× as long as two pairs of globular frontal setae, proclinate and elevated on separate, raised glossy tubercles ( Fig. 4B ); second pair reclinate, ¼ length of first globular-tipped orbital pair. One pair of post-ocellar setae, one pair of paravertical setae. One pair of inner vertical and one pair of outer vertical setae. Inner verticals undifferentiated from outer verticals and paraverticals. One row of postocular setae. Three rows of occipital setae. Two pairs of supravibrissal setae. One pair of vibrissae. Five pairs of subvibrissal setae.

Thorax ( Fig. 5A ): Grey-dusted throughout, with three dark brown vittae running along the dorsocentral and acrostichal setae, diffusing over scutellum. Six postpronotal setae. Two notopleural setae of equal length. Two postalar setae with one setula, posterior postalar seta 2× length of anterior postalar seta and thrice the length of intrapostalar seta. One pair of supra-alar setae. No strongly differentiated intra-alar setae. Dorsocentral setae 1+3; one strongly differentiated presutural pair, with two weaker preceding setulae, and one strongly differentiated apical postsutural pair preceded by two smaller pairs of dorsocentral setae approximately half the length of the former.Acrostichal setae poorly differentiated compared to the weak pairs of postsutural dorsocentral setae. Scutellum ( Fig. 5B ): One pair of apical setae, one pair of strongly developed subbasal setae, ⅔ the length of apical setae. One pair of weak basal setulae. No subapical setae, and discal setal area restricted to six weak setulae. Subscutellum bare. Two proepisternal setae. Two proepimeral setae, lower proepimeral setae slightly upcurved. Three strongly developed katepisternal setae of approximately the same length, forming an equilateral triangle (1:1:1) with three weak setulae inside the triangle.Anepimeron, meron and katepimeron bare, katatergite with fine hyaline hairs, anatergite bare. Wing hyaline and bare, with no conspicuous chaetation or suffusions. Haltere yellow.

Legs: Grey. Fore femur with one posterodorsal seta at least 2× as long as any other fore femoral setae; three preapical dorsal setae, four basal posteroventral setae, six evenly spaced posterior setae. Fore tibia with one preapical dorsal seta, one median and one preapical posterior seta. Mid femur with one strong supramedian anterior seta and two preapical posterodorsal setae. Mid tibia with one supramedian and one median posterodorsal seta. Hind femur with one dorsal seta basally and two anteroventral setae: one situated postmedially and the other preapically. Five evenly distributed anterodorsal setae on hind femur. Hind tibia with one median anterodorsal seta, one preapical posterodorsal seta, and one apical ventral seta. Trochanters are dark amber in colour.

Abdomen and terminalia: Grey-dusted throughout. Sternite 1 bare. Sternite 5 triangular in shape, with setae mainly on lobes ( Fig. 6A ). Sternite 6 with left and right arms forming ring, right arm interrupted before articulation; two pairs of dorsal setae, innermost pair crossing. Cercal plate rectangular in general shape with clear apical notch, two small dark processes apically ( Fig. 7A ). Surstylus fused with epandrium ( Fig. 8A ). Hypandrium tubular, with two flap-like structures on either side, hypandrial apodeme reduced, forming a sharp ridge. Aedeagus ( Fig. 9A ) with distiphallus slightly bent. Postgonite claw-shaped.

Holotype: ♂ SOUTH AFRICA: Western Cape: Oudtshoorn district, Moeras- // River Farm (209) // 33°48'S: 22°03'E 525 m asl // Early September 2007 [ix.2007], G.P.B. Davies, Dry Karoo scrub with flowers; [red label, red ink] Holotype // ♂ // 1806; Coenosia // macrotriseta sp. n. // det. B. Muller 2013; NMSA-Dip. 70333. NMSA type no. 1806. Genitalia dissected, with abdomen in vial under specimen.

Figures

Fig. 1. Lateral habitus: (A) Coenosia macrotriseta sp. n., ♂; (B) C. globuliseta Pont, ♂. Scale bar = 1 mm.

Figs 2, 3. (2) Head in lateral view: (A) C. macrotriseta sp. n., ♂; (B) C. globuliseta Pont, ♂. Scale bar = 0.5mm; (3) palpi: (A) C. macrotriseta sp. n., ♂; (B) C. globuliseta Pont, ♂. Scale bar = 0.2 mm.

Fig. 4. First pair of orbital setae of Coenosia macrotriseta sp. n., ♂: (A) apex, (B) base.

Fig.5. Coenosia macrotriseta sp.n., ♂, dorsal view:(A) thorax and (B) scutellum.Abbreviations:dc – dorsocentral seta, pprn – postpronotal seta, npl – notopleural seta, spal – supra-alar seta, pal – postalar seta. Scale bar = 0.2 mm.

Figs 6–9. Coenosia macrotriseta sp.n., ♂ (A) and C.globuliseta Pont, ♂ (B): (6) sternite 5, dorsal view; (7) cercal plate, dorsal view; (8)epandrium,surstylus and cercal plate, lateral view; (9) phallic complex, lateral view. Scale bar = 0.2 mm.