Isoperla bosnica Aubert, 1964

Murányi, Dávid, 2011, Balkanian species of the genus Isoperla Banks, 1906 (Plecoptera: Perlodidae), Zootaxa 3049, pp. 1-46 : 10-12

Isoperla bosnica Aubert, 1964 stat. rev.

( Figs. 21–25, 127)

Isoperla bosnica Aubert, 1964 — Aubert 1964: 297 (original description of male); Illies 1966: 396 (catalog)

Isoperla oxylepis balcanica Raušer, 1962 — Sivec 1980b: 9, Ikonomov 1986: 108 (synonymy not stated formally).

Material examined: Holotype male: BOSNIA-HERZEGOVINA: Trnovo , 13- 15.07.1929, leg. H. Zerny ( WNHM; penial armature prepared on slide No. 6, terminalia prepared on plastic sheet and pinned under the dry specimen, labels of the pinned specimen: I. bosnica / Aub / J. Aubert / dét. 1963; Typus; 55; Coll. Nat-Mus. Wien; Bosnien / Trnovo, 13.-15. / VII. ’29. Zerny); MONTENEGRO: Pljevlja municipality: Kozička Stream at its confluence with Ćeotina River, 26.06.2008, leg. V. Pešić: 1m ( HNHM; used for drawings, penial armature prepared on slide).

Diagnosis: This generally dark species is characterized by medial penial armature that is wide and distinctly folded, bearing long lateral expansions. Its scales are triangular and lateral penial armatures are lacking.

Description: Medium-sized species, macropterous. Body length: male 10.5 mm (n=1); forewing length: male 11.5 mm (n=2). General colour brown but the head and pronotum mostly yellow with dark brown markings; pilosity of the body and legs short and dense. Head yellow posteriorly and brown anteriorly, with a wide horseshoeshaped dark brown patch connecting the three ocelli, small light interocellar area closed posteriorly; tentorial callosities and M-line distinct, many wrinkles present both between the M-line, the antennal bases, and the tentorial callosities; occiput with dark brown rugosities, brown markings extend both laterally and medially ( Fig. 21). Eyes as large as the area delimited by the three ocelli. Scape dark brown, pedicel and the following three or four antennomeres brown, distal flagellomeres darker; palpi brown. Pronotum yellow, rectangular, edges angled; rugosities are large and brown, indistinct, anterior and posterior margins dark brown, but lighter medially. Mesonotum dark brown but yellow anteriorly, metanotum dark brown. Wings yellowish brown, subcosta and the venation of the basal fourth pale, other veins dark brown. Ventral surface of thorax mostly pale, meso- and metabasisternum mostly dark brown; furcasternites light brown, furcal pits brown ( Fig. 24). Femora brown, the dorsal surface and the ventral edges dark brown. Tibiae dark brown dorsally, paler ventrally; tarsi dark brown.

Male abdomen: First tergite dark brown but yellowish medially, tergites II–VIII entirely dark brown. Tergite IX somewhat lighter, tergite X pale brown with tripartite yellowish markings medially ( Fig. 22). Transverse row of four pigmented spots seen on all but tergite X. Sternites II and VIII–IX pale brown, sternites III–VII dark brown; sternites II–VII with a medial transverse row of four spots, sternite VIII with two spots. Vesicle of sternite VIII brown, as wide as long, its posterior margin is weakly rounded; as long as the one third of the segment’s length ( Fig. 23). Sternite IX bears dark brown patches anterolaterally, the medial penial armature visible through the posterior half of the segment. Paraprocts pale brown, sharp, thin and recurved; cerci dark brown.

Penis: Lobes and the distribution of colourless scales, hairs and sensilla cannot be studied because the specimens were collected without evertion of the penis. The medial penial armature is wide and distinctly folded with long lateral expansions, probably located on the ventral lobe ( Fig. 25); lateral penial armatures lacking. The central part of the medial penial armature is hemispherical but open both at the upper and the lower ends; lateral expansions abruptly tapering. Length 280 µm, width with the backfolded lateral expansions 1350 µm; width of the unfolded central part about 150 µm. Outstretched view of the medial penial armature shown in the original description ( Aubert 1964: Fig. 30). The scales are triangular and erect, cross section cylindrical; their length 30–50 µm, width 15–18 µm. The penis bears hydra-like scales around the lateral expansions of the medial penial armature, and small triangular scales more lateral to these.

Female, egg, larva: unknown.

Affinities: Isoperla bosnica was originally assigned to the rivulorum group sensu Consiglio 1961 ( Aubert 1964). Later Consiglio (1967) transferred it to the goertzi group; herein it is transferred to the oxylepis group. It was treated as a synonym of I. oxylepis balcanica by Sivec (1980b) and Ikonomov (1986), herein it is recognised as a valid species. It differs from the other species of the group by the presence of long lateral expansions on the medial penial armature and general dark colour.

Ecology and distribution: The species was originally described on the basis of a single male collected at Trnovo, SE Bosnia-Herzegovina in 1929 ( Aubert 1964). Despite intensive collecting, no additional specimens have been found in Bosnia-Herzegovina ( Kaćanski 1979) and the species was reported only from NW Macedonia ( Ikonomov 1979) in addition to the type locality ( Fig. 127). Later Ikonomov (1986) treated I. bosnica as a synonym of I. oxylepis balcanica . It is not clear if the Macedonian specimens refer to I. bosnica or to I. oxylepis balcanica . The species is new for the fauna of Montenegro, the single male being collected at the end of June from a submontane stream near its confluence with the Ćeotina River. It was collected with a male of I. tripartita tripartita and a pair of P. pallida .

Remarks: As already noted in the original description ( Aubert 1964), the holotype is in poor condition and the coloration is hardly visible. The redescription is based on the newly collected Montenegran specimen that agrees well with the holotype both in measurements and morphological features. The medial penial armature of the holotype is slide mounted, distorting the lateral edges, resulting in a similar appearance of this structure to that found in I. oxylepis . This may have resulted in the incorrect synonymy with I. oxylepis balcanica ( Ikonomov 1986) .