Thaumatoniscellus speluncae n. sp.

(Figs 1–21)

Material examined. Holotype. Male, Pit 3 near Banina Stream, Veprinac, Učka, Istria, Croatia, (Gauss- Krieger coordinates x=5019084, y=5440933), 05.IV.2008, leg. J. Bedek (Inv. No IT 1287, CBSSC, CNHM). Paratypes. 1 female and 1 juvenile, leg. J. Bedek (Inv. No IT 996; CBSSC, CNHM); 1 female, leg. J. Bedek (Inv. No 1092, DBE). Topotypes. 1 female, ibid., 04.XI.2006, leg. M. Pavlek (Inv. No IT 772, CBSSC, CNHM); 2 males and 2 females, ibid., 17.IX.2007, leg. J. Bedek (Inv. No IT 1056, CBSSC, CNHM); 2 males and 3 females, ibid., 17.IX.2007, leg. J. Bedek (Inv. No 1093, DBE).

Diagnosis. Small species (up to 1.45 mm long). Median pair of tubercles on posterior part of cephalon small. Pereon tergites with 2 pairs of prominent tubercles per side. Male pleopod 1 endopodite constricted in median part; exopodite stout, terminally widened, without setae. Maxilla 1 exopodite with elongated teeth, compared with T. orghidani. Maxilla 2 outer lobe remarkably shorter than inner lobe, with 1 rod-like seta on tip. Anchor-like lateral protrusions weakly developed in comparison with T. orghidani. Male pereopod 7 propodus twice as long as dactylus.

Description of male holotype. Body length 1.45 mm. Cephalon (Figs 2–3) short and wide, frontally compressed, bearing 2 rows of rounded tubercles: frontal row with large median tubercle and 2 smaller tubercles; posterior row of 6 tubercles, median pair very small. Lateral lobes short and wide, ventrally oriented.

Pereon (Figs 1–4) prominently convex with a row of 4 pronounced rounded tubercles.

Pleon (Figs 4–5) prominently convex; pleonal segments 3–5 with developed epimera. Pleonal segment 3 with medial pair of rounded tubercles and traces of paramedial pair.

Pleotelson (Fig. 5) post dorsal surface and posterior margin concave.

Integument ornamented with net of polygonal cells bordered with line of granules (Figs 3–6). Characteristic scale-setae with a spindle-shaped basal part and fan-shaped apical part (Fig. 6) on exposed parts of dorsal body surface (tubercles, cephalon, pleotelson and margins of the body segments), frontal sides of antenna and uropodal protopodite.

Antennula (Fig. 12) of 3 articles, similar in length; apex bearing 3 aesthetascs with dorsal surface grooved.

Antenna (Fig. 13) with stout pedunclar articles; flagellum three segmented, as long as article 5.

Right mandible with 1 penicil; pars incisiva with 3 teeth; lacinia mobilis absent.

Left mandible without penicils; pars incisiva lateralis with 3 teeth; pars incisiva medialis of molar form; pars molaris oval in shape.

Maxilla 1 exopodite (Fig. 8) with 3 strong elongated outer teeth, 5 inner teeth, 3 of them very short; 2 stick-like setae paramedially, 1 very elongated and 1 short; endopodite (Fig. 7) with 3 short and stout penicils, terminal one with rounded apex.

Maxilla 2 (Figs 9–10) outer lobe narrow, remarkably shorter than inner lobe, with 1 strong rod-like seta on tip; inner lobe with row of elongated rod-like setae on dorsal side, ventral side with brush-like surface of dense, very tiny setae.

Maxilliped (Fig. 11) basipodite with rounded latero-distal margin with rows of sparse elongated thin setae; palp with three lobed apex, bearing strong setae terminally, row on medial edge and 1 on outer edge; endite conical, with elongate penicil terminally and spine-like protrusion on medio-distal margin, large seta subapically near inner margin.

Pereopods 1–7 similar in shape, with stout articles; without noticeable secondary sexual characteristics; merus as long as wide, carpus longer than wide (Figs 14–15). Pereopod 1 with 6 comb-like rows of fine setae on frontal surface of propodus; one row distally on carpus (Fig. 14). Pereopod 7 propodus twice as long as dactylus (Fig. 15).

Genital papilla (Figs 16–17) with narrowed terminal part elbows to dorsal side, anchor-like terminally, with tip directed dorsally.

Pleopod 1 (Figs 18–19) exopodite voluminous, laterally constricted in the medial part; lateral margin of basal part widely convex; terminal part with complex three-dimensional structure; with a wide and short conical apophysis distally, laterally-oriented elongated terminal lobe bottle-shaped, mediodistally folded and without apical denticles; wide tetragonal lobe dorsally oriented. Endopodite (Fig. 19) shorter than exopodite, stout, terminally slightly widened, without spine-like setae.

Pleopod 2 (Figs 20–21) exopodite short with protruded mediodistal margin and spine-like setae on distal margin. Endopodite, triarticulated, slightly sigmoidal (lateral view) (Fig. 21); distal article elongated, spiniform; medial article twice as long as basal article; basal article wider than long.

Uropod exopodite and endopodite conical, subequal in size. Endopodite articulated more proximal than exopodite.

Etymology. The species is named after the Speleological Organisation “Spelunka“ from Veprinac, Istria. The name is a noun in the genitive singular.