Sericostoma flavicorne Schneider 1845

Sericostoma flavicorne Schneider 1845

(Figs 1–5)

Material examined. Turkey, Muğla, Fethiye, Gelemiş, 45 km North, Seki Stream, 100 m, 36°29′N, 29°17′E, 22.v.1999, 16 males, 7 females, (CD: U-116); Fethiye, Dereköy (Kemer), 1800 m, 36°39′N, 29°28′E, 26.vi.1988, 2 males, (CD: U-50); all leg. and coll. SİPAHİLER.

General description. Antennae brown, scapes black; first 10–12 segments beyond scapes dark brown and annulated subapically; maxillary palps (Fig 1) gradually rounded, hemispherical in lateral view. Wings dark brown, forewings with pale spots. Length of each male forewing 10.5–12.5 mm (mean = 11.42 mm, n = 7), of each female forewing 10.0–13.0 mm (mean = 11.87 mm, n =4). In addition, maxillary palps of males of this species large, like those of other Turkish species of Sericostoma.

Male genitalia (Figs 2–5). Segment IX roundly dilated anterolaterally, forming 80° angle (Fig 2), posteroventral margin projecting in 80° angle in middle (Fig 4). Preanal appendages oval, 1/4 as long as lateral prolongations of segment X. In dorsal view, median part of segment X rounded at tip (Fig 3); sclerotized lateral prolongations of segment X broad, each with 3 short, acute branches: basoventral, mesoventral, and dorsal branches. In lateral view, basoventral branch directed ventrad, attenuated apically; mesoventral branch half as long as dorsal branch; dorsal and mesoventral branche directed posteroventrad, (Fig 2). In dorsal view, each sclerotized lateral prolongation of segment X dilated subapically and forming small, pointed projection on inner edge. Inferior appendages each with dorsal branch broadly dilated subapically, especially on caudoventral edge, subapicoventral lobe rounded and basal of U-shaped notch on subapicoventral margin; ventral branch of each inferior appendage slender, slightly dilated subapicolaterally (Figs 2, 4). Phallic apparatus narrow at base, evenly curved 90° near middle and gradually and slightly broader towards tip; basoventral carina triangular and as long as thickness of base.

Diagnosis. McLachlan (1898) gave a figure of the sclerotized lateral prolongations (penis sheaths) of the male genitalia of Sericostoma flavicorne, which is the most diagnostic feature for this species complex. In a redescription of this species, variations in the features of the males collected from the type locality were reported (SİPAHİLER 2000).

Sericostoma flavicorne is similar to S. mesopotamicum.As seen in these figures, the variations are very small and the diagnostic characteristics of the genitalia can be summarized as follows: In lateral view, the lateral prolongations of segment X are broad, each has its basoventral branch short and its apex is attenuated and directed ventrad; the mesoventral branch is short, acute apically, and directed posterad, the dorsal branch is dilated subapically and has a small, more or less pointed projection located halfway along the inner edge. In S. mesopotamicum the lateral prolongations of segment X are more-slender in lateral view, the basoventral branch is shorter, the mesoventral and dorsal branches are more slender than those of S. flavicorne, the dorsal branch is somewhat curved dorsad. In dorsal view, the apical branches are almost parallel to each other, without subdistal dilations or small, pointed projections on the inner edges, and are directed caudad.

Remarks. Whereas S. mesopotamicum occupies a rather large area in eastern and southeastern Turkey, Sericostoma flavicorne occurs in southwestern Turkey in the tributaries of Kocaçay (Eşen Çayı), usually inhabiting rapidly flowing water.