Icosta (Ardmoeca) omnisetosa Maa, 1969

Icosta (Ardmoeca) omnisetosa Maa, 1969 View in CoL , stat. n.

Figs 1–5 View Figs 1–3 View Figs 4–5

MATERIAL EXAMINED. Russia: Chukotka Autonomous Region, Anadyrsky District, Meinypilgyno, on pintail snipe Gallinago stenura , 2.VI 2019, 1 ♀, coll. P. Tomkovich. The specimen in ethanol is deposited in the collection of the Zoological Institute of the Russian Academy of Sciences , St. Petersburg .

DESCRIPTION (female from Chukotka). Head and thorax length combined 2.8–3 mm.

Head dark brown. The width of the eye is one fourth of the width of the head. The vertex on the posterior margin is approximately 2 times wider than the eye. The parafrontals are wide. The setae on the parafrontals are yellow. One of them is strong and long. The forehead front is V-shaped, the horns form a sharp curve. Palpus is 1.5 long as antenna.

Mesonotum dark brown and mostly bare. Humeral tubercles approximately cone-shaped, protruding anterolaterally. Among the small yellow setae, there are 2 long setae – dark and yellow. Prescutum sparsely feebly striate all over. About 20 laterocentral yellow setae on each side on prescutum. About 7 yellow setae on each side of scutum. Large setae are located almost in the middle of the upper row.

Scutellum posterolaterally rounded, posteriorly distinctly convex. Interdistance of bases of scutellar setae more than 2 median length of scutellum. Ventral side of thorax light with brown triangles on sides. Prosternum well sclerotized, semicircular, with 2–3 pairs of setae. Mesosternum roundly shallowly notched.

Wing length 5.0 mm. Wing with 2 transverse veins and correspondingly with 2 closed basal cells 1bc and 2bc. Longitudinal veins R 1, R 2+3 and R 4+5 connecting with Costa at acute angle. Section on Costa between juncture of R 1 and R 2+3 twice as long as section between juncture of R 2+3 and R 4+5. Costa and basicosta covered with hairs. Microtrichia covering almost entire wing except for thin strip at lower edge of wing.

Legs brown. Ventral side of femur 3 densely uniformly setose except an oval bare area at base. Claws bifid. Empodium and paired pulvilli not reduced.

Abdomen rather uniformly covered with moderately long and stout setae. On the dorsal side the median area is largely bare. Tergite 3 is small, well sclerotized to a shiny spot only in the center. Tergite 6 is large, reaching the edges of the abdomen. Its dorsal margin is almost straight, and its apical margin is notched. On the ventral side of the abdomen, bare areas are located only in the basal part and around the genital area. In the upper half of the abdomen the setae are denser. From there, in the apical direction, on each side there is a narrow vertical stripe of dense setae.

REMARKS. Till now Icosta holoptera is divided in two subspecies, nominotypical I. holoptera holoptera Lutz, 1915 distributed in USA (Massachusetts, Ohio, Pennsylvania, South Carolina, Wisconsin) ( Bequaert, 1954), Brazil (State of Rio de Janeiro) ( Lutz et al., 1915) and Colombia ( Bequaert, 1965) and I. holoptera omnisetosa Maa, 1969 known from New Guinea, Philippines, Malaya, China (Chekiang) ( Maa, 1969), Japan (Okinawa) ( Mogi et al., 2002), and Amur Region in Russia ( Meissner et al., 2020). Specimens from the Old World have 1 long seta on the posterior edge of the inner orbit, a postvertex without a distinct depressed spot, the inner corner of the horns is V-shaped, the edge of the ridge on the dorsal side of the horns with a small projection. Specimens from the New World have two long setae on the posterior edge of the inner orbit, a postvertex with a clearly depressed spot, the inner corner of the horns is U-shaped, and the edge of the ridge on dorsal side of the horns is smooth and straight. The shape of the horns is an important species feature, as shown in Doszhanov (2003). Therefore, we propose that I. omnisetosa stat. n. should be considered as distinct species.

The specimen from Chukotka differs from I. omnisetosa by one seta on humeral tubercles, bare area in the top of basal part, continuing down to sides in upper third of female abdomen ventral side and vertical stripe of dense setae, continuing to sides in down part, and absence of vertical stripe of dense setae.

HOSTS. The specimen from Chukotka was collected on the pintail snipe Gallinago stenura (Bonaparte, 1831) . This bird breeds in northern Russia and migrates to spend the non-breeding season in southern Asia ( Pakistan, India, Sri Lanka, Southeast Asia, and Indonesia). As the hosts of I. omnisetosa were listed Amaurornis phoenicurus (Pennant, 1769) , Gallinago stenura , Gallinula tenebrosa Gould, 1846 , Lanius cristatus (Linnaeus, 1758) , Lewinia striata (Linnaeus, 1766) , Porphyrio melanotus (Temminck, 1820) , Rallus pectoralis Temminck, 1831 and Zapornia tabuensis (Gmelin, 1789) ( Maa, 1969) . In Japan I. omnisetosa was found on A. phoenicurus and Gallinago hardwickii (Gray, 1831) ( Mogi et al., 2002) .

At the same time, in Brazil, I. holoptera was found on red-winged tinamou Rhynchotus rufescens (Temminck, 1815) , a ground-living bird from central and eastern South America, and on Aramides saracura (Spix, 1825) , living in Argentina, Brazil, Paraguay and Uruguay ( MacArthur, 1948). The male of I. holoptera was described from Thamnophilus unicolor grandior Hellmayr, 1924 distributed in Colombia, Ecuador, and Peru ( Bequaert, 1957).