Isoperla albanica Aubert, 1964

Murányi, Dávid, 2011, Balkanian species of the genus Isoperla Banks, 1906 (Plecoptera: Perlodidae), Zootaxa 3049, pp. 1-46 : 16-20

Isoperla albanica Aubert, 1964

( Figs. 43–61)

Isoperla albanica Aubert, 1964 — Aubert 1964: 296 (original description of male and female); Illies 1966: 393 (catalog); Zwick 1973: 241 (catalog).

Material examined: Holotype male: ALBANIA: Skala Bicajt (Kukës district, Shkallë Bicaj, gorge of the Tershanë Stream at Bicaj ), 17.06.1918 ( WNHM; penial armature prepared on slide Nr. 5, terminalia prepared on plastic sheet and pinned under the dry specimen, labels of the pinned specimen: Coll. Nat-Mus. Wien; I. albanica / Aub / J. Aubert / dét. 1963; Typus; 2; Alban. Exped. / Skala Bicajt / 17. VI. 1918) ; Paratype female: same locality and date ( WNHM; labels of the pinned specimen: I. albanica / Aub / J. Aubert / dét. 1963; Paraypus; Alban. Exped. / Skala Bicajt / 17. VI. 1918) ; Paratype male: Gjalica Ljums (Kukës district, Mts Gjalica e Lumës ), 17– 26.06.1918 ( WNHM; terminalia with penis prepared on plastic sheet and pinned under the dry specimen, labels of the pinned specimen: I. albanica / Aub / J. Aubert / dét. 1963; Paratypus; Alban. Exp. 1918 / Gjalica Ljums / 17–26. VI.) ; Shkodër district: Okol, Mts Prokletije, stream along the path towards Pejë Pass , N 42°24.496’ E 19°45.271’, 1010m, 30.05.2005, leg. K. Balogh, Z. Barina, D. Murányi, D. Pifkó: 1f ( HNHM) ; brook along the path towards Pejë Pass , N 42°24.510’ E 19°45.300’, 1000m, 30.05.2005, leg. K. Balogh, Z. Barina, D. Murányi, D. Pifkó: 1m 1f ( HNHM; penial armature prepared on slide) ; Dibër district: Radomirë, Mts Korab , spring and stream E of the village, N 41°49.032’ E 20°30.016’, 1440 m, 26.06.2007, leg. L. Dányi, Z. Erőss, Z. Fehér, A. Hunyadi, D. Murányi: 3m 17f ( HNHM; used for drawings, one male terminalia and eggs prepared for SEM), 2m 2f ( CGV) ; torrent E of the village, N 41°49.131’ E 20°30.160’, 1460 m, 26.06.2007, leg. D. Murányi: 3m 11f ( HNHM) ; AUSTRIA: Burgenland: Kobersdorf , 18.05.1996, leg., det. W. Graf: 3m ( CWG) .

Diagnosis: This small, generally dark species is characterized by a triangular penial armature on the median lobe, its scales being dart-shaped and thin. Lateral penial armatures lacking. In females the subgenital plate has shallow, narrow medial notch that continues anteriorly to form a short sulcus on the posterior margin.

Description: Small-sized species, macropterous. Body length: males 8.0– 9.5 mm (n=12), females 10.5–12.0 mm (n=32); forewing length: males 9.5–11.0 mm (n=14), females 10.0– 11.5 mm (n=33). 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, with an H-shaped dark brown patch connecting the three ocelli and the apical parts of the M-line; tentorial callosities and M-line distinct, occiput with brown rugosities laterally ( Fig. 43). Eyes as large as the area delimited by the three ocelli. Scape dark brown, pedicel partly yellowish brown, the following three or four antennomeres are yellowish brown but distal part of the antenna is dark brown; palpi brown to dark brown. Pronotum yellow, rectangular, edges angled; rugosities are small but numerous and brown coloured, anterior and posterior lines brown under and above the rugosities. Mesonotum dark brown but yellow anteriorly and medially, metanotum dark brown. Wings yellowish, venation pale in the anterior fourth, costa and the other parts brown. Ventral surface of thorax mostly pale, meso- and metabasisternum mostly dark brown; furcasternites light brown, furcal pits black ( Fig. 46). Femora pale but the dorsal surface and the ventral edges brown. Tibiae brown, tarsi dark brown.

Male abdomen: First tergite dark brown but yellowish brown medially. Tergites II–VII dark brown, tergites VIII–IX paler, tergite X yellowish brown ( Fig. 45). Transverse row of four pigmented spots seen on all segments. Sternites II–VII brown with a medial transverse row of four spots. Sternite VIII paler and with a dark pattern, but only two spots. Vesicle of sternite VIII brown, usually much longer than wide, its posterior margin is rounded; as long as half the segment’s length ( Fig. 44). Sternite IX yellow but with dark brown patches anteriorly and laterally, the medial penial armature hardly transparent in the posterior half. Paraprocts dark brown, sharp, thin and recurved; cerci dark brown, base of the first cercal segment usually paler.

Penis: Divided into six lobes and a basal section in extruded position ( Figs. 48–51). The medial penial armature located on the ventral lobe, lateral penial armatures lacking. The medial penial armature a narrow triangle, broadest toward basal section; length 450 µm, width 300 µm ( Fig. 52). The scales are dart-shaped, most of them are slightly bent ( Figs. 53–54). The length of the longer ones in the basal part is 80–100 µm, width 10 µm; shorter scales of the apical part are about 30 µm. The ventral lobe is elongated, covered with sausage-like scales with hairy tip around the apical part of the medial penial armature ( Fig. 54). These scales are grading into smaller triangular ones towards the medio-apical part of the lobe which is bald; into branched hair-like scales towards the lateral and the basal parts. Along the basal part of the medial penial armature only simple hair-like scales occur, basolateral areas of the ventral lobe bald. The medial lobe is long and narrow, bearing triangular scales on its end at the ventral lobe ( Fig. 57). These scales are grading into a few hydra-like scales, then stout triangular hairy scales towards the central part ( Fig. 58); apical part bald and smooth. The upper lateral lobes are long and their ventral part curved downwards. They bear a strip of elongated triangular hairy scales mixed with a few sensilla along the medial lobe ( Fig. 56), from its ventral origin to the dorsal fifth. Besides this strip, most of the lobes covered with branched and simple hair-like scales but the ventral and dorsal tips are bald. The lower lateral lobes are smaller than the upper ones, and their medial areas bear small, hydra-like scales mixed with sensilla ( Fig. 55); ventral and dorsal parts bald. The basal section bears sparse simple hair-like scales.

Female abdomen: First tergite yellow anteriorly and medially, posterior margin dark brown. Tergites II–VII dark brown, tergites VIII–IX paler, tergite X brown only anteriorly and medially, other parts yellowish brown. Transverse row of four pigmented spots seen on all segments. Sternites II–VII brown with a dark brown transversal anterior line interrupted in the middle, and a medial transverse row of four spots. Subgenital plate covers most of the sternite VIII and the anterior part of sternite IX; anterior part of sternite VIII brown, darker anteriolaterally. Most of the plate yellowish, lateral margins dark at least in the medial section; posterior margin rounded with a characteristic, shallow and usually narrow medial notch that continues in a short sulcus on most of the specimens ( Fig. 47). Sternite IX yellow, but bears two brown lateral patches on the posterior half. Sternite X and the paraprocts yellow; cerci dark brown, base of the first cercal segment usually paler.

Egg: Chorion dark brown, 0.30–0.32 mm long and 0.18–0.22 mm wide (n=30). Shape rectangular, cross section quadrangular; narrowing towards the collar end, sides slightly depressed ( Fig. 59). Hatching line inconspicuous. Micropyles placed in a transverse row close to the opercular end, not raised, each located on the meeting point of carinae between the follicular cell impressions (FCIs) ( Fig. 61). Chorion with marked ornamentation of penta- or hexagonal FCIs with usually two excrescences in their centres. Collar round, rim slightly flanged; bears one row of FCIs ( Fig. 60). Anchor not studied.

Larva: unknown.

Affinities: The species was originally assigned to the rivulorum group sensu Consiglio 1961 ( Aubert 1964); later Consiglio (1967) transferred it to the saccai group sensu Consiglio 1967. Herein, it is transferred to the albanica group. It differs from the closely related I. belai by lacking lateral and having triangular medial penial armatures. The female is unique in the genus with a shallow medial notch that continues as a short sulcus on the posterior margin of the subgenital plate (not apparent in a minority of specimens).

Ecology and distribution: The species was originally described from the Gjalica e Lumes Mountains ( Aubert 1964). This is in close proximity to the Korab Mountains from where the new material was collected. It has also been reported from Montenegro, Bosnia-Herzegovina and Serbia ( Sivec 1980a), Macedonia ( Ikonomov 1986), SE Germany ( Weinzierl 1999), Austria ( Graf 1999, Konar 1999, Ruzicka 2001) and Western Slovakia ( Krno 2003) which suggests an Eastern Alpine–Illyrian distribution. The present data mark its current southern limit. This species was collected in June from the Korab Mountains in high gradient streams above 1400 m. The first location also produced I. oxylepis balcanica , while the second yielded I. citrina as well. The species was quite numerous at both localities and found on bushes, sedges, and Petasites leaves.

Remarks: Though the vesicle of sternite VIII of the types and the Austrian specimens are much wider than shown in Fig. 44, these are not as wide as in the original description ( Aubert 1964: Fig. 25). The female paratype has a wide, but more rounded medial notch on the subgenital plate than described by Aubert (1964: Fig. 24).