Typhloiulus clavatus Antić, 2018

Typhloiulus clavatus Antić View in CoL , new species

Figs 9 View FIGURE 9 , 10 View FIGURE 10 , 15A View FIGURE 15

Material examined: Type specimens. Holotype male, CROATIA, Dalmatia , Otok , Stražbenica, Klenovac Pit ( 43.708100°N, 16.776683°E), 30 April 2016, T. Rađa leg. ( NHMSC) GoogleMaps . Paratype female, same data as for holotype GoogleMaps .

Diagnosis. Typhloiulus clavatus is most similar to members of the subgenus Inversotyphlus , viz. T. lobifer , T. gellianae , and herein described T. gracilis and T. opisthonodus . These species are characterized by the presence of a very long opisthomere with a similarly shaped velum; the presence of a poorly developed, but visible opisthomeral lamella; and similar male sexual and habitus structures (see Discussion). The new species differs clearly in gonopod details, such as the presence of a robust promere with the apical half slightly curved anteriad and the presence of a very prominent and clavate mesomere.

Description. Based on holotype (male) 20 mm long, vertical diameter of the largest body ring 1.35 mm, body with 41 podous rings + 3 apodous rings + telson. Colouration: ( Fig. 9A View FIGURE 9 ). Brownish. Head: ( Fig. 9B View FIGURE 9 ). Labrum with three labral teeth, with 4 supralabral and 7+7 labral setae. Gnathochilarium with promentum kite-shaped, elongated; lamellae linguales with 4+3 setae in one row, stipites each with 3 setae. Antennae 2 mm long, length 148% of vertical diameter of the largest body ring. Length of antennomeres I–VIII (in mm): 0.12 (I), 0.42 (II), 0.36 (III), 0.31 (IV), 0.36 (V), 0.26 (VI), 0.12 (VII), and 0.05 (VIII). Length/width ratio of antennomeres I–VII: 0.75 (I), 2.8 (II), 2.4 (III), 2 (IV), 2 (V), 1.6 (VI), and 1 (VII). Antennomeres V and VI each with a terminal corolla of large bacilliform sensilla; antennomere VII with a terminal corolla of microsetae. Body rings: ( Fig. 9D View FIGURE 9 ). The whole metazonal area with longitudinal striations. Metazonal setae fallen off. Telson: ( Fig. 9C View FIGURE 9 ). Epiproct with a long preanal process, strongly curved downwards and covered by long dorsal and lateral setae. Paraprocts rounded, with numerous long setae. Hypoproct lenticular, with five long setae. Legs: First pair of legs modified, hook-shaped ( Fig. 10A View FIGURE 10 ); coxa, postfemur, and tibiotarsus each with one seta, prefemur with four or five setae, femur with two or three setae. Tibiotarsus with a small tarsal remnant in the form of a prominent dorsal lobe. The tip of the first pair of legs tuberculate. Second pair of legs with poorly developed ventral pads on the tibia. Penis: ( Fig. 10B View FIGURE 10 ). Bilobed. Lobes prominent, elongated. Ventral margin of body ring 7: ( Fig. 9E View FIGURE 9 ). Well-developed, tapering distad, with rounded tip. Posterior margin right-angled to metazona. Gonopods: ( Figs 10C–F View FIGURE 10 , 15A View FIGURE 15 ). Promere ( p) and mesomere ( m) robust, both shorter than opisthomere ( o). Promere ( p) shorter than m; apical half slightly curved anteriad; laterally in the form of a shield; mesal lobe ( ml) wide, subquadrangular, with three apical setae; telopodite ( t) subcylindrical, tapering distad, over high ml. Mesomere ( m) clavate in lateral/mesal view, subapically with anterior tuberculation. Opisthomere ( o) slender, straight, and elongated; antero-mesally with poorly developed lamella ( l); mesally with one spine; velum ( v) unipartite, well-developed, tapering anteriad, with fimbriated tip. Solenomere ( s) narrow, distally with several short spines.

Paratype (female) 25 mm long, vertical diameter of the largest body ring 1.5 mm, body with 47 podous rings + 2 apodous rings + telson.

Distribution. This species is known only from its type locality, Klenovac Pit in Dalmatia ( Fig. 20 View FIGURE 20 , red circle).

Notes. Klenovac Pit is some 45 m deep and also inhabited by a stygobiotic Niphargus sp. ( Amphipoda ).

Etymology. To denote the presence of a club-shaped mesomere. Adjective.