Rukuluk, Haddad, 2025

Rukuluk gen. nov.

Type species.

Rukuluk gramineus sp. nov.

Diagnosis.

Members of Rukuluk gen. nov. share with Namaquella gen. nov. and Poachelas the pale body with adaptations to grass-living but can be distinguished from the former by the very different genitalic morphology and more elongate body, and from the latter by the lack of paired spines ventrally on the anterior legs. Males of Rukuluk gen. nov. can be recognized from all other trachelid genera by the distinctive palpal morphology, particularly the presence of retrolateral grooves in the cymbium that correspond to the RTA and distal section of the embolus (Figs 26 A View Figure 26 , 27 C View Figure 27 ) and the long membranous basal section of the embolus, which gradually narrows to a long, whip-like tip (Figs 21 K – N View Figure 21 , 26 A, B View Figure 26 ); the latter trait is most similar to the embolus morphology of Poachelas ( Haddad and Lyle 2008: figs 91, 97). Females are distinguished by the elongate subrectangular atrium that extends almost the entire length of the epigynal plate (Figs 26 E View Figure 26 , 27 D View Figure 27 ), with long looping membranous copulatory ducts and small posterolateral spermathecal structures internally (Figs 27 E View Figure 27 , 28 D View Figure 28 ).

Description.

Small spiders, 3.06–3.20 mm in length; carapace bright creamy-yellow to yellow-brown; carapace oval, broadest at posterior of coxae II, gradually narrowed towards eye region (Fig. 21 A, F View Figure 21 ); fovea distinct, a short narrow slit (Fig. 22 A View Figure 22 ); posterior margin very slightly concave, almost straight (Fig. 22 A View Figure 22 ); carapace weakly convex in lateral profile, slightly elevated from clypeus to approximately ½ carapace length, with steeper slope in posterior quarter (Fig. 21 B, G View Figure 21 ); carapace surface finely wrinkled, densely covered in short fine curved setae with small tuberculate bases (Fig. 22 A – C View Figure 22 ). All eyes surrounded by black rings (Fig. 21 A, F View Figure 21 ); AER strongly procurved in anterior view (Fig. 22 B View Figure 22 ), slightly recurved in dorsal view (Fig. 22 C View Figure 22 ); clypeus height slightly larger than ⅘ AME diameter at AME in males, ⅔ AME diameter at AME in female, ½ ALE diameter at ALE in males, slightly less than ⅖ ALE diameter at ALE in females; AME slightly larger than ALE; AME separated by distance approximately ⅓ their diameter; AME separated from ALE by narrow sliver, almost touching; PER slightly recurved, PME and PLE equal in diameter in males, PME very slightly larger than PLE in females; PME separated by distance equal to ⅚ their diameter; PME separated from PLE by distance approximately ½ PME diameter. Chilum distinct, split; cheliceral promargin and retromargin each with two teeth (Fig. 22 D, E View Figure 22 ); fang with distinct serrula; endites with lateral margins converging slightly distally, mesal margins with longitudinal groove and dense maxillar hair tuft (Fig. 22 F View Figure 22 ), distal margins with distinct serrula comprising sharp straight denticles (Fig. 22 G View Figure 22 ); labium trapezoidal, slightly longer than wide, narrower distally than basally (Fig. 22 F View Figure 22 ). Pleural bars sclerotised, isolated; sternum oval, with straight anterior margin (Fig. 22 H View Figure 22 ), two pairs of slit sensilla present between first two coxal pairs (Fig. 22 I View Figure 22 ); longer than broad, broadest at posterior of coxa II, surface smooth centrally, densely covered in long, slightly curved setae with small tuberculate bases (Fig. 22 H, I View Figure 22 ); precoxal triangles present, intercoxal sclerites present between coxae I and II and II and III only. Leg formula 1423 in males, 4123 in females, densely covered in short fine setae with tuberculate bases (Figs 21 D, E, I, J View Figure 21 , 23 A – D, I, J View Figure 23 ); legs I swollen, more so in males (Fig. 21 A View Figure 21 ) than females (Fig. 21 F View Figure 21 ), femora with slightly convex dorsal surface, ventral surface almost straight (Fig. 21 D, I View Figure 21 ); all femora strongly constricted proximally; patellar indentation on retrolateral side narrow, with lyriform organ at proximal end (Fig. 23 B, C View Figure 23 ); anterior legs of both sexes with dense ventral scopulae in paired strips separated by strip with sparse setae, denser in females (Fig. 23 A, D – J View Figure 23 ) than males (Fig. 24 A – F View Figure 24 ); tibiae (at least) with ovoid pore-containing sensilla laterally (Fig. 24 G, H View Figure 24 ); males with ventral cusps on metatarsi and tarsi I and II (Figs 24 C, E View Figure 24 , 25 A, B View Figure 25 , 27 A View Figure 27 ), absent on tibiae and in females; metatarsi with strongly developed metatarsal stopper (Figs 23 H, I View Figure 23 , 24 F, I View Figure 24 ), metatarsi III and IV with weak distal preening brush and distinct comb (Figs 21 E, J View Figure 21 , 24 l View Figure 24 ); tarsi with numerous long and short dorsal trichobothria and chemosensory setae (Fig. 23 I, J View Figure 23 ); trichobothria with slightly lowered distal plate, distal margin of hood overlapping plate, hood with four curved ridges, roughly concentric (Fig. 25 D, E View Figure 25 ); tarsal organ at approximately ⅘ tarsus length on anterior tarsi (Fig. 23 J View Figure 23 ), ovoid, only very slightly elevated from integument, surface finely wrinkled, opening oval and distally placed (Fig. 25 F, G View Figure 25 ), possibly absent on tarsus IV (Fig. 25 C View Figure 25 ); tarsal claws short, with nine teeth, of which the basal two are broad and spatulate and the distal seven slender and elongate (Fig. 23 L View Figure 23 ), with dense tenant setae forming claw tufts in between (Fig. 23 I – L View Figure 23 ). Abdomen oval, clearly larger in females (Fig. 21 F View Figure 21 ) than males (Fig. 21 A View Figure 21 ), with dorsal scutum in males only (Fig. 25 H View Figure 25 ); dorsum covered in fine setae, two pairs of distinct sigilla in both sexes; venter without large sclerites or markings (Fig. 21 C, H View Figure 21 ), covered in fine setae (Fig. 25 I View Figure 25 ). Spinnerets short, conical, in compact group, only studied in detail in females: ALS with two MAmp and 10 Pi (Fig. 25 J View Figure 25 ); PMS partly obscured, with only two mAmp, one Cy and three Ac distinguished (Fig. 25 K View Figure 25 ); PLS partly obscured, with two Cy and nine Ac distinguished (Fig. 25 L View Figure 25 ). Male palpal femora and patellae without apophyses (Fig. 26 A View Figure 26 ), patella with retrolateral lyriform organ (Fig. 26 D View Figure 26 ); palpal tibiae with retrolateral trichobothrium (Fig. 26 A, C View Figure 26 ), thumb-like vRTA and long slender dRTA that corresponds with retrobasal groove on cymbium (Fig. 26 A View Figure 26 ); tegulum V-shaped, narrower proximally and broader distally; embolus very long, originating retrolaterally, with membranous looping base and midsection, narrowing to long slender whip-like tip (Figs 26 B View Figure 26 , 27 B, C View Figure 27 ), part of its length corresponding to retrodistal cymbial groove (Fig. 26 A View Figure 26 ). Female epigyne very weakly sclerotized, with large subrectangular keyhole-shaped atrium, with median split visible under S. E. M. (Fig. 26 E View Figure 26 ) but not light microscopy (Fig. 27 D View Figure 27 ), weakly distinguishable under compound microscopy (Fig. 28 View Figure 28 ); copulatory openings situated at anterior of atrium; copulatory ducts membranous, entirely translucent, their path only visible after staining, curving anteriorly and laterally, before bending back along their interior margin before looping towards posterior, running along margin of atrium before entering lateral ST II near midpoint of epigyne, with short duct connecting them to posterior ST I.

Etymology.

The name is an arbitrary combination of letters. Gender feminine.