Alpioniscus (Illyrionethes) lossinii n. sp.

(Figs 5–8, 15)

http://zoobank.org/ 47E3E7D2-262F-4D2C-B50E-3C3322043DC2

Alpioniscus strasseri . —Bedek et al. 2011: 278 (partim: Medvjeđa špilja).

Alpioniscus (Illyrionethes) sp. 2.— Bedek et al. 2019: figs 3, 5.

Material examined. Croatia, Croatian Littoral, Mali Lošinj Island: Holotype male Ćunski, Rt. Lokvica, Medvjeđa špilja (cave), 44.6055°N, 14.4079°E, 25–28 March 2010, leg. J. Bedek (CBSSC IT4224).

Paratypes. 4 males, 1 male juv., 13 females, 3 juvs, same data as holotype (CBSSC IT2397); 1 male, 8 females, same locality, 20 March 2005, leg. J. Bedek (CBSSC IT2398); 2 males, 2 females, same locality and date, leg. M. Lukić (MZUF 9846); 3 males, 5 females, same locality, 6 March 2010, leg. B. Jalžić (CBSSC IT2400); 1 male, same locality, 2 March 2010, leg. J. Bedek (CBSSC IT2402) .

Description. Maximum length: male, 4.9 mm; female, 5.3 mm. Colourless body, pereon with almost parallel sides, pleon narrower than pereon (Fig. 5A,B). Dorsum granulated, with ridges near posterior margins of cephalon, pereonites and pleonites 1–2, and some triangular scale-setae (Fig. 5C). Some gland pores on lateral margins of pleonites 4, 5 and telson (Fig. 5E).

Cephalon (Fig. 5D) with suprantennal line bent downwards in middle; antennal lobes rounded. Eyes absent. Posterior margin of pereonite 1 convex, of pereonites 2, 3 straight, and of pereonites 4–7 progressively more concave (Fig. 5A). Pleonites 3–5 with small posterior points visible in dorsal view (Fig. 5E). Distal part of telson with concave sides and broadly rounded apex (Fig. 5E).

Antennula (Fig. 5F) of three articles, distal article bearing five to seven aesthetascs. Antenna (Fig. 5G) with peduncle granulated; flagellum of eight to 10 articles with one row of aesthetascs on four to five different articles, always on a second and third article. Buccal pieces (Fig. 6) as in A. magnus .

Pereopods similar in shape, ungual seta simple, dactylar seta bifid and setose (Fig. 7A).

Uropod (Fig. 5E) with protopod slightly grooved on outer margin; endopod distinctly shorter than exopod, proximally inserted.

Male: Pereopod 1 (Fig. 7A) carpus bearing five to six setae. Pereopod 1 and 2 with propodus and carpus bearing numerous short scales on rostral surface. Pereopods 5 and 6 with small lobe proximally on sternal margin. Pereopod 7 (Fig. 7B,C) ischium with straight sternal margin; merus with slightly concave sternal margin and proximally with small hookshaped lobe bearing up to five triangular scales and one large seta; carpus with straight sternal and tergal margins.

Genital papilla (Fig. 8A) with rounded apical part.

Pleopod 1 (Fig. 8A) exopod with distal part narrow and rounded apex, concave outer margin, slightly convex inner margin; endopod narrow, triangular, armed with long apical plumose seta.

Pleopod 2 (Fig. 8B) exopod subtriangular with slightly concave outer margin; endopod of two articles, slightly longer than exopod, distal article with posterior part narrower with strong and subapically bifid terminal seta.

Pleopod 3–5 exopods as in Fig. 8 C–E.

Etymology. The species is named after the island of Lošinj (Lat. Lossinium).

Remarks. The new species is characterized by the lack of a hump on the tergal margin of the male pereopod 7 carpus, together with A. (I.). haasi (Verhoeff, 1931b), A. (I.) heroldi (Verhoeff, 1931a), A. (I.) herzegowinensis (Verhoeff, 1931a), A. (I.) kratochvili (Frankenberger, 1938), A. (I.) tuberculatus (Frankenberger, 1939), A. (I.) verhoeffi (Strouhal, 1938) and the two new species described below, A. (I.) drazinai and A. (I.) mandalinae . It differs from all these species by the narrow distal part of the male pleopod 1 exopod; from A. (I.) heroldi and A. (I.) herzegowinensis also in the shape of the hook on the male pereopod 7 merus.