Hercostomus exarticulatus ( Loew, 1857 )

Grichanov, I. Ya., Nourti, M. & Kettani, K., 2020, The Hercostomus exarticulatus species group in the Palaearctic Region (Diptera: Dolichopodidae), Caucasian Entomological Bulletin (Caucas. entomol. bull.) 16 (1), pp. 27-34 : 28-31

Hercostomus exarticulatus ( Loew, 1857)

( Figs 1–8 )

Gymnopternus exarticulatus Loew, 1857: 18 .

Hercostomus exarticulatus ( Loew, 1857) : Mik, 1880: 357. Becker, 1917: 215; Stackelberg, 1934: 142, figs 87–88; Parent, 1938: 165, figs 213–217; Negrobov, 1991: 85.

Hercostomus (Gymnopternus) exarticulatus ( Loew, 1857) : Mik, 1884: 181.

Hercostomus papillifer Mik, 1880: 353 , figs 1–5 (synonymized by Mik, 1884: 181) (type locality: Austria, “bei Hütteldorf nächst Wien ”).

Hercostomus tanjusilus Negrobov et Zurikov in Negrobov et al., 1988: 219, syn. n. (type locality: Georgia, Lagodekhi Reserve , 2000 m).

Material. 1♂ ( ZIN), Romania, “Herculesbad, 19.06.1871 ”, “716”, “ Hercostomus exarticulatus Lw., Kowarz det.” ; 1♀ ( ZIN), Italy, “Varena, 1876”, “718”, “ Hercostomus papillifer Mik, Kowarz det.”, “ Hercostomus exarticulatus Lw. , det. Grichanov ” ; 4♀ ( ZIN), Abkhazia , “Gagra, 9.09.1937 (Filipiev)”, “ Hercostomus exarticulatus Lw. , det. Stackelberg ” .

Diagnosis. Fore coxa mainly blackish or brown; fore and/or hind femora largely blackish or brown, or only hind femur with brown strip along anterior side; hind tibia dark at apex; hind tibia with weakly sclerotized rounded dorsolateral apical projection bearing minute spike; outer hypandrial arm with thick L-shaped curvation projecting ventrally; inner hypandrial arm straight, with subapical dorsal tooth; cercus wholly brown.

Notes. Loew [1857] did not mention ventral tubercle at base of mid femur in his description of Gymnopternus exarticulatus . Mik [1880] distinguished his Hercostomus papillifer from other then known species by that character in addition to the others. He mentioned also H. exarticulatus , but noted that the latter had much darker femora. Mik [1884] considered the two species as varieties of H. exarticulatus ; one with darker legs known from the type locality (Triest) and Romania (Iron Gates near Herсulesbad (= Băile Herculane) and another variety with lighter legs known at that time from Austria and Northern Italy. Later the species was reported from many countries, from the Canary Islands and Morocco in the West to Tajikistan and Kyrgyzstan in the East [Grichanov, 2017]. However, careful examination of the material published by Negrobov and Rodionova [2004] has revealed that females from Kyrgyzstan and Tajikistan must be associated with H. exarticulatoides , including one female topotype. Females mentioned by the same authors from the Caucasus and Voronezh Region of Russia belong most probably to the true H. exarticulatus . This species was collected on the Canary Islands and redescribed by Santos Abreu [1929]. It was collected and mentioned there again by Frey [1936], who considered the Canarian species H. canariensis as a colour variety of H. exarticulatus . However, Santos Abreu clearly stated that his species has broad shining black tooth between male tibia and tarsus in contrast to small spine at the same place in H. exarticulatus . The latter species was insufficiently described and illustrated [ Loew, 1857; Mik, 1880; Santos Abreu, 1929; Stackelberg, 1934; Parent, 1938]. Moreover, Mik [1884], Becker [1917], Stackelberg [1934] and Parent [1938] noted dark-legged and light-legged varieties. Therefore, we provide here photos of colour characters of a specimen from Romania (mentioned by Mik [1884]), suggesting that the old records from Morocco, Spain and France (e.g. [ Vaillant, 1956]) can belong to either H. exarticulatus or H. canariensis .

Hercostomus tanjusilus was described by single holotype collected from the southern slopes of the Greater Caucasus mountain range, which has historically been considered a natural barrier between Eastern Europe and Western Asia. Hercostomus tanjusilus description and schematic drawings of hypopygium correspond to the morphology of H. exarticulatus male collected from Romania. The only difference is the colour of coxae. They were described [ Negrobov et al., 1988] as metallic green in H. tanjusilus (including fore coxa), but being blackish or black in H. exarticulatus . We consider this character as a colour variation and place the former name in synonymy to the latter name.

Distribution. Type locality: Italy, Triest. Palaearctic: Morocco, Algeria, Spain (incl. Canary Isl.), France, Netherlands, Belgium, Germany, Austria, Italy, Hungary, Romania, Russia (Voronezh), Abkhazia, Georgia, Armenia. The species occurs also in the Republic of Adygea ( Russia) (O.P. Negrobov, personal communication, 2019).

Figures

Figs 1–8. Hercostomus exarticulatus (Loew, 1857). 1 – habitus; 2 – head; 3 – wing;4 – mid femur; 5 – hitching lock between hind tibia and basitarsus, ventrolateral aspect; 6 – hitching lock between hind tibia and basitarsus, dorsolateral aspect; 7 – hypopygium, ventral view; 8 – apex of hypopygium, lateral view. Рис. 1–8. Hercostomus exarticulatus (Loew, 1857). 1 – общий виΑ; 2 – гоΛова; 3 – крыΛо; 4 – среΑнее беΑро; 5 – сцепΛение заΑней гоΛени и Λапки, виΑ снизу сбоку, 6 – сцепΛение заΑней гоΛени и Λапки, виΑ сверху сбоку, 7 – гипопигий, виΑ снизу, 8 – вершина гипопигия, виΑ сбоку.