Spilogona ciliatocosta (Schnabl, 1915)

Sorokina, Vera S., 2025, New taxonomic notes on the genus Spilogona Schnabl, 1911 (Diptera: Muscidae) in Arctic Russia, with the description of three new species, Zootaxa 5584 (1), pp. 1-25 : 11-12

Spilogona ciliatocosta (Schnabl, 1915)

Limnophora (Spilogona) ciliatocosta Schnabl in Becker et al., 1915: 31. Type-locality: “in der Karskaja Tundra” [ RUSSIA, West Siberia , Yugorskiy peninsula, Kara district; vii.1909; collector F. Zaitsev] [seen].

Spilogona contigua Huckett, 1965: 18 , 190, 201 (key), and 216. Type-locality: “ Spence Bay , Northwest Territories, 7.14.51 [i.e. 14.vii.1951], J.G. Chillcott ” [ CANADA, NWT] [seen]. Syn. nov.

Spilogona ciliatocosta (Schnabl, 1915) ; Sorokina, 2012a: 331 (Taymyr Peninsula); Sorokina & Thidrikh, 2021: 219 (Chukotka AO, incl. Wrangel Island ) .

Notes. The type material of Limnophora ciliatocosta (in ZISP) and Spilogona contigua (in CNC) was examined. The descriptions of both species and the male terminalia are the same. However, the illustrations of the male terminalia of Spilogona ciliatocosta by Hennig (1959a: Taf. XV, Fig. 299) and of Spilogona contigua by Huckett (1965: 352, Fig. 165) are slightly different in the width of the surstylus. I examined many specimens of Palaearctic Spilogona ciliatocosta and Nearctic Spilogona contigua and I have concluded that the width of the surstylus depends on the angle of viewing the terminalia and is variable. The cercal plate of these species is very distinctive because of the different length of right and left cerci ( Huckett, 1965: 346, Fig. 96). Hennig in his monograph illustrated the male terminalia ( Hennig, 1959a: Taf. XIII, Fig. 276; 1959b: Taf. XVIII, Fig. 361) of a specimen from Wrangel Island named as “ Limnophora macropyga Frey ” (det. A. Stackelberg). These figures correspond well with both ciliatocosta and contigua . I examined this specimen and found that the terminalia is mounted on a permanent slide preparation, which is why it is slightly compressed, and the surstylus thus appears wider than that of the Hennig’s figure of the type of Limnophora ciliatocosta . Unfortunately, the terminalia of the syntype of Limnophora ciliatocosta is also mounted on a poorly prepared permanent mount, and it was impossible to describe the form and exact width of the surstylus.

Specimens of both sexes of these species are distinctive, with a completely black body, facial edge projecting beyond level of profrons, mid tibia with v setae and hind femur without pv setae, scutellum with downwardly-directed preapical setulae on upper border of declivities, shining prementum, and costa with costal spinules. I therefore conclude that Spilogona contigua Huckett, 1965 is a new junior synonym of Limnophora ciliatocosta Schnabl, 1915 .

In the ZISP, apart from the male syntype of Limnophora ciliatocosta there is a female named as Limnophora ciliatocosta . The locality is the same as the male (Karskaja Tundra). However, this specimen does not agree with the male syntype of Limnophora ciliatocosta . Hennig (1959a) also had doubts about the identity of this female. The female syntype of Limnophora ciliatocosta does not have the facial edge projecting beyond level of profrons, costa with very strong costal spines, mid tibia without v setae and hind femur with several pv setae, proboscis short and thickened, prementum dusted, body with grey dust, not black, thorax grey with three distinct brown longitudinal stripes and with 2+3 dc setae, abdomen wet, but with traces of paired brown spots, postgenital plate with hairs. This female is definitely a different species and the specimen runs to Spilogona tornensis (Ringdahl, 1926) .

Spilogona ciliatocosta is very similar to Spilogona tundrae (Schnabl, 1915) . These species can be separated as following couple:

1 Larger species (5–6 mm), costal setulae weak. Male: fore tibia with p seta in middle; fronto-orbital plates separated by a wide frontal vitta, which is as wide as width of outer margins of ocelli or wider; abdomen shining; anal segment swollen, when viewed in profile bulging towards the dorsal region. Female: abdomen blackish............................. S. tundrae

- Smaller species (4–4.5 mm), costal setulae coarsened proximad of costal spine. Male: fore tibia without p seta in middle; fronto-orbital plates touching or separated by a narrow frontal vitta; abdomen subshining; anal segment flattish or appressed dorsad, not bulging toward the dorsal region. Female: abdomen bronzy....................................... S. ciliatocosta

All of the characters given above for Spilogona ciliatocosta and Spilogona tundrae are variable, but are more commonly as stated in the couplet. The male terminalia provides the most reliable identification character.

Distribution. PALAEARCTIC: Russia (Arctic Siberia and Far East). NEARCTIC: Alaska, Yukon, NWT, Quebec.