Endonura caeca Gisin 1963

Endonura caeca (Gisin, 1963)

Figs 19–24, Tab. 4

Neanura caeca: Gisin 1963: 3.

Type material. Holotype: adult male on slide, Bosnia and Herzegovina, Igman, Veliko Polje, 1200 m a. s. l., spruce forest Piceetum excelsae, 9.III.1961. leg. H. Gisin (MHNG).

Diagnosis. Habitus typical of the genus Endonura. Dorsal tubercles present and well developed. Eyes absent. Buccal cone short, labrum nonogival. Head with chaetae A, B, C, D, E, O, F and G. Tubercles Cl and Af separate. Tubercles Dl and (L+So) on head with 3 and 9 chaetae respectively. Tuberles Di on th. I present. Tubercles De on th. II and III with 3 and 4 chaetae respectively. Tubercles L on abd. III and IV with 3 and 6 chaetae respectively. Abd. IV and V with 8 and 3 tubercles respectively. Claw without inner tooth.

Redescription. Habitus typical of the genus. Body length of holotype (without antennae): 0.6 mm. Colour of the body white, eyes absent (Fig. 19).

Types of dorsal ordinary chaetae. Macrochaetae Ml thickened, short, straight, narrowly sheathed, feebly serrated, apically rounded or pointed (Figs 19, 23–24); macrochaetae Mc and Mcc thickened, straight, pointed or rounded at apex; mesochaetae and microchaetae short, thin and pointed.

Head. Buccal cone short with labral sclerifications nonogival (Fig. 20). Labral and labial chaetotaxy impossible to recognize. Maxilla and mandible invisible. Dorsal chaetotaxy of ant. III and IV as in Fig. 21. Schaetae of ant. IV of medium length and thickened, S1 and S2 slightly thinner than others. Apical vesicle unilobed (Fig. 22). Chaetotaxy of other part of antennae impossible to recognize. Chaetotaxy of head as in Tab. 4 a and Fig. 19. Tubercles Cl and Af separate. Chaetae D connected with tubercle Cl, chaeta E free. Tubercle Dl with 3 chaetae, chaetae Dl2–3 and Dl6 absent (Fig. 19). Tubercle (L+So) with 9 chaetae, chaeta So2 absent. Elementary tubercle BE absent (Fig. 19). Chaeta A shorter than B. Chaetae Ocp longer than A.

Thorax, abdomen, legs. Body s-chaetae thin and smooth, shorter than nearby macrochaetae (Fig. 23). Chaetotaxy of th. and abd. as in Tab. 3 b and in Figs 19, 23–24. Tubercles Di on th. I well developed, not fused with De (Fig. 19). Chaetae De2 on th. II–III and De3 on th. III connected with tubercle De. Chaetae De3 on abd. I–III connected with tubercle De (Fig. 23). Chaetae De2 on th. III and abd. I–III nearly equal chaetae De3. The line of chaetae De1–chaeta s perpendicular to the dorsomedian line on abd. I–III. Tubercles Di on abd. V fused (Fig. 24). Tubercle L on abd. IV with 6 chaetae. No cryptopygy. Chaetotaxy of ventral side of abdomen and legs impossible to recognize.

Discussion. Among eyeless species of the genus, E. caeca is most similar to E. arbasensis Deharveng, 1979 (known from France and Spain, Deharveng 1979, Jordana et al. 1997), particularly in having an unpigmented body and complete chaetotaxy of central area of head. However, they differ in numerous details, including the number of chaetae Dl and (L+So) (in caeca 3 and 9 respectively, in arbasensis 6 and 10), the presence/absence of free chaetae De on th. III and abd. I–III (in caeca absent, in arbasensis present), the number of chaetae L on abd. IV (in caeca 6, in arbasensis 7) and the number of ordinary chaetae (De+Dl+L) of abd. V (in caeca 5, in arbasensis 7).