Elongeuma, Golovatch, 1982

KEY TO SPECIES OF ELONGEUMA View in CoL

1(2) Larger: length of adults ca 14 mm. Coloration pallid, only 5 light brown ocelli on each side of head. ♂ legs 7 with a pair of strong hooks on coxae and small glandular parabasal knobs of prefemora ( Fig. 26 View Fig ). Coxal pouches (cs) of posterior gonopods with membranous projections ( Fig. 31 View Fig ) ................................................... E. speophilum View in CoL

2(1) Smaller: adults up to 10 mm long. Coloration usually yellow-brown, adults and subadults often with distinct patterns. Up to 16–18 ocelli black. ♂ legs 7 otherwise. Coxal pouches (cs) of posterior gonopods either totally suppressed or with small and coniform projections .................................................................... 3

3(4) ♂ legs 7 leg-like, as in Figs 3 View Figs 3–7 and 9 View Figs 8–18 . Solenomere (sl) of anterior gonopods ( Figs 5, 6 View Figs 3–7 , 10, 12 View Figs 8–18 ) with a distinct midway lobule (j). Posterior gonopods particularly strongly reduced ( Fig. 5 View Figs 3–7 ), usually without coxal pouch vestige ................................................ E. reductum sp.n.

3(4) ♂ legs 7 with strongly reduced, 2-segmented telopodites ( Fig. 19 View Figs 19–23 ). Solenomere (sl) of anterior gonopods ( Figs 21, 22 View Figs 19–23 ) without lobule j. Coxal pouches (cs) of posterior gonopods with distinct and coniform projections ( Fig. 23 View Figs 19–23 ) ....................................................... E. chichkan sp.n.

Further notes on and a new diagnosis of Elongeuma

As the genus Elongeuma presently comprises already three described species, an analysis of intrageneric variations is possible. Because the original description of the type species E. speophilum (ZMUM, holotype restudied, see above) and illustrations [ Golovatch, 1982] erred in several accounts (28, not 30, body segments, largely blunt metatergal macrochaetae, ♂ legs 7 mistakenly referred to and depicted as legs 6 etc.), most of which were corrected later [ Golovatch, Wytwer, 2003], a fully rectified redescription has been given below.

The most pronounced variations in Elongeuma spp. seem to concern ♂ leg-pair 7 and the posterior gonopods. Indeed, whereas ♂ legs 7 are eventually leg-like in E. speophilum and E. reductum sp.n., with modifications mainly affecting the coxa, it is surprisingly strongly reduced in E. chichkan sp.n. ( Fig. 19 View Figs 19–23 ). In E. reductum sp.n., particularly strong reduction concerns the posterior gonopods, with the coxite not being hypertrophied, and the coxal pouch vestige usually being totally missing ( Figs 7 View Figs 3–7 , 10, 15–17 View Figs 8–18 ).

Traditionally, the presence or absence of ♂ tarsal papillae has been considered as a family-rank character (e.g. Attems [1926], Verhoeff [1926 –1932] or Minelli [2015]). Tarsal papillae present in Elongeuma spp. only in ♂ legs 3– 6(7), these often being restricted to the distalmost parts of the tarsi, is rather unusual as compared to the remaining three genera and species of Kirkayakidae (cf. Golovatch, Wytwer [2003]).

Genus Elongeuma Golovatch, 1982 View in CoL

Type species: Elongeuma speophilum Golovatch, 1982 , by original designation.

DIAGNOSIS. Body small (adults 8–14 mm long), with 28 segments (26p+1a+T), juloid, devoid of paraterga. Clypeus flattened (♂) or regularly convex (♀). Metatergal macrochaetae mostly bacilliform. Gnathochilarium without promentum. Collum usual, not covering the head from above. Tegument smooth.

Legs long and slender, ♀ legs 2 normal; only ♂ legs 3– 6(7) with tarsal papillae, ♂ legs 7 modified; both ♂ legs 10 and 11 with coxal sacs.

Anterior gonopods placed on a plate-like sternum with retained tracheal apodemes; coxites always independent, contiguous medially, clearly curved caudad, held parallel to each other to slightly crossing each other distally, tripartite: each composed of a pair of lateral hyaline lamellae (hl); more mesally with a pair of longer, conspicuously divided solenomeres (sl), each conspicuously barbed/fringed distally; and a pair of mesal, very long pseudoflagella (pfl) (or true flagella as derivatives of coxal glands?). Posterior gonopods far more simple, also placed on a plate-like sternum with retained tracheal apodemes, mostly composed of medially contiguous, elongated, sac-shaped and setose coxites either fully devoid of coxal pouches or retaining their vestiges (cs) medially near base.