Chirosiomima gestroi ( Séguy, 1930 ), Seguy, 1930

Michelsen, Verner, 2014, Taxonomic assessment of Chirosiomima Hennig (Diptera: Anthomyiidae), with proposal of a new genus for Hylemyia curtigena Ringdahl, Zootaxa 3790 (1), pp. 86-102 : 88-91

Chirosiomima gestroi ( Séguy, 1930)

( Figs. 1, 2 , 4–9 , 12 , 13 )

Hylemyia gestroi Séguy, 1930: 88 , figs. 4, 5.

Chirosiomima gestroi (Séguy) ; Hennig 1966: 30 (in part: Libya and Tunisia); Hennig 1976a: 928 (in part: Libya and Tunisia).

Identity of Hylemyia gestroi Séguy. Séguy (1930) described this species primarily from a single female from Al Jaghbub (“Giarabub”) [29°44′N 24°30′E], a Libyan oasis in the desert near the Egypt border. It was collected in March 1927 by M. Confalioneri. A 1st instar larva retrieved from this female was also described. Supplementary material available to Séguy was an unspecified number of females from Bou-Hedma in Tunisia collected in March and April [1929] by M.C. Dumont. When Hennig (1966) revised this species in a new genus, Chirosiomima , he considered the Libyan female deposited in the Museo Civico di Storia Naturale, Genua, and labelled “Cotypus” as the holotype of Hylemyia gestroi . This I regard as a lectotype designation by inference. Hennig further noted that he had seen Séguy’s supplementary material from Tunisia consisting of 20 females deposited in the Paris Museum. These should be regarded as paralectotypes of Hylemyia gestroi . I have not seen the type material of Hylemyia gestroi , but have been able to examine additional material, consisting of both males and females, from Tunisia collected by M. C. Dumont. I found the specimens in a box with unsorted Diptera on a visit to the Paris Museum in 1985. The female holotype of Hylemyia gestroi Séguy from Libya is no doubt conspecific with the species of Chirosiomima occurring in Tunisia.

Because he had no males from either Libya or Tunisia, Hennig (1966) based his redescription of Chirosiomima gestroi (Séguy) , with illustrations of the male and female genitalia, on specimens in the Stuttgart Museum collected in Iran in 1954 by W. Richter & F. Schäuffele. This was unfortunate, as the present study revealed significant differences in the male and female terminalia between specimens from Tunisia and Iran, respectively. As detailed below, Hennig’s redescription of “ C. gestroi (Séguy) ” refers actually to a different species, C. obscurinervis ( Emden, 1941) .

Material examined. TUNISIA: Gafsa Prov.: Bou-Hedma, 85km E Gafsa [34°28'N, 9°34'E], 1♂ 8♀ iv.1929, 1 ♂ 19♀ v.1929 (C. Dumont) [ MNHN, ZMUC]. Tozeur Prov.: Tozeur [33°55'N, 8°07'E], 1♀ 2.v.1921 (C. Dumont) [ MNHN]. ISRAEL: Negev (“Southern Palestine ”): Treibe, 1♀ 1.v.1953 (O. Theodor) [ TAUI].

Description. Very similar to C. obscurinervis (Emden) , but different as follows:

Upper part of parafrontalia, at level of antennal bases, with a less well defined brownish spot ( Fig. 1 ). Ground colour of thorax invariably wholly dark, that of abdomen extensively dark with postabdomen and sometimes hind margin of tergite V ochre yellow. Legs including tarsi wholly ochre yellow, or femora more or less darkened. Wing without darkening and clouding of cross-veins r–m and dm–cu. Male: Sternite V ( Fig. 4 ) with moderately enlarged, simple setae on posterior lobes. Surstyli ( Figs. 5–7 ) longer and distally wider, with a distinct incision near apex. Female: Sternite VI ( Figs. 12 , 13 ) enlarged but evenly convex, not forming a hump on posterior part.

Distribution. Recorded from Libya and Tunisia ( Séguy 1930). Presently also from Israel. Records from Iran ( Hennig 1966) refer to the following species, C. obscurinervis .

Biology. Virtually nothing is known. The localities suggest that the species lives exclusively in arid semidesert, dune and steppe biomes, often in the vicinity of oases. Séguy (1930) showed that the female is capable of keeping an incubated egg with a 1st instar larva in the vagina. This phenomenon called simultaneous viviparity ( Meier et al. 1999) is not uncommon (unpubl. obs.) among anthomyiid taxa breeding in short-lived organic substrates. On a collecting trip to Tunisia in March 1986 I searched without success after Chirosiomima gestroi in the Bou-Hedma area where C. Dumont collected most of his specimens on several occasions back in 1929.

Figures

FIGURES 1 – 3. Chirosiomima spp. 1. C. gestroi, male from Tunisia, habitus. 2. Same, labella. 3. C. obscurinervis, female from Iran, habitus. Scale bars: 1 mm (1, 3); 0.1 mm (2).

FIGURES 4 – 9. Chirosiomima gestroi, male from Tunisia. 4. Sternites IV and V. 5 – 7. Hypopygium in posterior, posterolateral and lateral views. 8. Hypandrium, pregonites, left postgonite and vertical sclerite, anterolateral view. 9. Phallus, lateral view, and ejaculatory pump. Scale bar: 0.25 mm.

FIGURES 10 – 12. Chirosiomima spp. 10. C. obscurinervis, male from Iran, sternites IV and V. 11. C. obscurinervis, lectotype male from Ghana, hypopygium, posterolateral view. 12. C. gestroi, female from Tunisia, oviscapt, flat mount (s = sternite; sp = spiracle; t = tergite). Scale bars: 0.25 mm.

FIGURES 13, 14. Chirosiomima spp., oviscapt, lateral view. 13. C. gestroi, female from Tunisia (s = sternite; sp = spiracle; t = tergite). 14. C. obscurinervis, female from Iran (arrow: hump on sternite VI). Scale bar: 0.25.