Lessertina Lawrence, 1942

Haddad, Charles R., 2014, A revision of the endemic South African sac spider genus Lessertina Lawrence, 1942 (Araneae: Eutichuridae), Zootaxa 3873 (1) : -

Lessertina Lawrence, 1942

Type species: Lessertina mutica Lawrence, 1942 , by monotypy.

Lessertina Lawrence, 1942: 173 ; Dippenaar-Schoeman & Jocqué, 1997: 129; Bosselaers & Jocqué, 2000: 318.

Diagnosis. Lessertina is a distinctive genus that can be easily recognised from the other Afrotropical Eutichuridae ( Tecution Benoit, 1977 , Cheiracanthium and Cheiramiona ) by the subrectangular carapace with strongly raised, domed cephalic region, the wide separation of the lateral eyes from the medians (by at least twice the diameter of medians) and the relatively closely positioned median eyes (separated by a distance approximately equal to their diameter), and their black colouration ( Figs 1–5 ).

Description. Medium-sized spiders, 6.25–8.20 mm in length; carapace surface finely wrinkled, sparsely covered in very short straight white setae; several short curved setae in eye region; carapace subrectangular, rounded posteriorly, eye region broad, carapace broadest at posterior of coxa II ( Figs 1, 2, 4 ); cephalic region dome-shaped, highest at 2⁄5 carapace length, thoracic region with gradual slope ( Fig. 5 ); fovea absent, but very shallow depression at ⅔ carapace length, marked by narrow dark line; posterior margin slightly concave. All eyes surrounded by black rings; AER procurved, PER straight, MOQ narrower anteriorly than posteriorly, slightly wider than long. Chilum distinct, triangular, split medially; chelicerae very large and bulging ( Fig. 5 ), especially in males, anterior surface of paturon coarsely wrinkled, covered in short white bristles, posterior surface with many transverse ridges ( Fig. 6 ); cheliceral boss prominent; fangs long and oblique; cheliceral promargin and retromargin with several small teeth, promargin with single large tooth; promarginal escort seta absent; promarginal rake setae finely plumose, with tuberculate bases; endites elongate, notched laterally, with longitudinal prolateral ridge, distinct serrula and dense maxillar hair tuft on mesal margins; labium trapezoidal, longer than wide, narrower anteriorly; anterior margin concave, with transverse groove near base. Pleural bars sclerotised, isolated; sternum shield-shaped, longer than broad, rebordered; surface finely granulate, covered sparsely in short straight white setae, with erect straight setae scattered around margins; precoxal triangles small, distinct; intercoxal sclerites present between coxae I & II and II & III in L. mutica females and L. capensis sp. nov. males, also between coxae III & IV in L. mutica males. Leg formula 4123; legs covered in very short straight setae ( Figs 7–15 ); retrocoxal window very small; trochanters with shallow notch; patellar indentation narrow, broader at proximal end ( Figs 7, 8 ); legs with isolated short spines on femora and anterior metatarsi ( Figs 9–12 ), sometimes also on posterior tibiae; metatarsi and tarsi with scopulae ( Figs 10, 14 ), posterior metatarsi with distal preening brush ( Fig. 13 ); tibiae, metatarsi and tarsi with several dorsal trichobothria ( Figs 14, 15 ); paired tarsal claws short, situated laterally, with very dense claw tufts in between ( Fig. 14 ); female palpal tarsus with several slit sensilla, palpal claw broad and spatulate ( Figs 16, 17 ). Abdomen oval, black, with or without markings, covered in very short straight white setae; dorsal scutum absent; two pairs of dorsal sigilla present, first at approximately ⅓ AL and second at midpoint; epigastric region weakly sclerotised except for booklungs; venter without post-epigastric sclerites or ventral sclerite; two paired rows of tiny sclerites run mediolaterally from epigastric furrow to spinnerets; inframamillary sclerite present, weakly sclerotised and small; venter covered short straight white setae. Spinnerets: ALS of male ( Fig. 18 ) and females ( Fig. 21 ) with single major ampullate gland spigot, single adjacent nubbin and several piriform gland spigots; PMS of male ( Fig. 19 ) with one large minor ampullate gland spigot and many aciniform gland spigots; PMS of female ( Fig. 22 ) one small minor ampullate gland spigot, one tartipore and many aciniform gland spigots; PLS of male ( Fig. 20 ) with many aciniform gland spigots; PLS of female ( Fig. 23 ) with only aciniform gland spigots distinguished. Male palp with large retrolateral apophysis; cymbium oval, dorsally with weak cymbial scopula in distal half and several short rod-like setae at distal end ( Fig. 27 ); ventrally with a bunch of dense setae near embolus tip and conductor, patch denser and larger in L. mutica than L. capensis sp. nov.; embolus long, originating proximally, curving around prolateral margin of tegulum, fine at distal end, tip hidden behind large sclerotised subtriangular distal conductor; sclerotised median apophysis fine and hook-shaped, placed in membranous cavity on retrolateral distal side of tegulum. Female epigyne with strongly sclerotized longitudinal ridges anteriorly ( Fig. 24 ), forming lateral margins of slightly bulging plate ( Fig. 25 ), with copulatory openings at anterior end ( Fig. 29 ); copulatory ducts initially directed posteriorly, looping before entering coiled anterior ST II, with broad duct leading to round mediolateral ST I ( Figs 26 , 30 ).

Figures

FIGURES 1 – 5. General habitus of Lessertina mutica Lawrence, 1942 (1 – 3) and L. capensis sp. nov. (4, 5): 1, 4. Male, dorsal view; 2. Female, dorsal view; 3. Live female from Silaka Nature Reserve; 5. Male, lateral view. Scale bars: 1, 2, 4, 5 = 2 mm.

FIGURES 6 – 17. Scanning electron micrographs of Lessertina mutica Lawrence, 1942 male (6) and female (7 – 16): 6. Chelicera, posterodistal view; 7. Patella IV, arrow indicating patellar indentation; 8. Same, detail of lyriform organ at proximal end of patellar indentation; 9. Femur IV, proximal spine; 10. Metatarsus II, distal ventral spine and scopula; 11. Same, distal spine enlarged; 12. Metatarsus IV, lateral spine; 13. Same, distal ventral preening brush; 14. Tarsus II, claw tuft, arrows indicating trichobothria; 15. Same, detail of trichobothria; 16. Palpal tarsus, arrows indicating single slit sensilla; 17. Same, palpal claw enlarged.

FIGURES 18 – 23. Scanning electron micrographs of Lessertina mutica Lawrence, 1942 male (18 – 20) and female (21 – 23) spinneret morphology: 18, 21. Anterior lateral spinneret; 19, 22. Posterior median spinneret; 20, 23. Posterior lateral spinneret. Abbreviations: Ac – aciniform gland spigot (s); MAmp – major ampullate gland spigot (s); mAmp – minor ampullate gland spigot (s); n – nubbin; Pi – piriform gland spigot; ta – tartipore. Photos by Martín Ramrez.

FIGURES 27 – 32. Genitalic morphology of Lessertina mutica Lawrence, 1942 (27 – 30) and L. capensis sp. nov. (31, 32): 27, 31. Male palp, ventral view; 28, 32. Same, retrolateral view; 29. Epigyne, ventral view; 30. Vulva, dorsal view. Abbreviations: C—conductor; CD—copulatory duct; CO—copulatory opening; EB—embolus base; ET—embolus tip; FD—fertilisation duct; MA—median apophysis; MDS—modified distal cymbial setae; ST—spermathecae I and II. Scale bars: 0.5 mm.

FIGURES 24 – 26. Scanning electron micrographs of Lessertina mutica Lawrence, 1942 female genitalic morphology: 24. Epigyne, ventral view; 25. Same, posterior view; 26. Same, dorsal view. Abbreviations: CD – copulatory duct; EP – epigynal plugs in copulatory openings; FD – fertilization duct; ST – spermathecae I and II. Photos by Martín Ramírez.