Orthobula Simon, 1897

Haddad, Charles R., Jin, Chi & Platnick, Norman I., 2022, A revision of the spider genus Orthobula Simon, 1897 (Araneae: Trachelidae) in the Afrotropical Region. I. Continental species, Zootaxa 5133 (3), pp. 355-382 : 358

Genus Orthobula Simon, 1897

Orthobula Simon, 1897a: 152 ; Deeleman-Reinhold 2001: 431 .

Type species. Orthobula impressa Simon, 1897 , by original designation.

Diagnosis. Orthobula shares with Capobula the large number of paired ventral spines on the anterior tibiae and metatarsi, and the absence of ventral cusps in both sexes. In somatic morphology, Afrotropical species of Orthobula have pits across the entire carapace surface, including along the midline ( Figs 13–16 ), while absent along the midline in Capobula ( Haddad et al. 2021: figs 11, 14) and some Asian species of Orthobula . Female Orthobula can be distinguished by the posteriorly positioned spermathecae (as opposed to laterally positioned in Capobula ), while male Orthobula can be recognized by the considerably inflated palpal tegulum (only as wide as cymbium in Capobula ), the narrow, finely coiled embolus (longer, uncoiled and retrolaterally directed in Capobula ), and the absence of a patellar apophysis (present in Capobula ).

Description. Small spiders, 1.30–2.70mm in length; carapace orange-brown to wine-red, frequently with mottled black markings ( Figs 1–12 ); carapace oval, broadest at coxae II, eye region narrow; fovea absent, only a short shallow depression ( Fig. 13 ); posterior margin slightly concave; carapace surface finely wrinkled, with series of deep pits forming striate patterns over entire surface ( Figs 13–16 ), each pit with central pore, often plugged with unknown exudate ( Fig. 14 ); surface sparsely covered with scattered fine curved setae, particularly in eye region ( Figs 13–16 ). All eyes surrounded by black rings, weakly developed around PME ( Figs 1–12 ); AER procurved in anterior view, recurved in dorsal view ( Figs 15, 16 ); AME very slightly larger than ALE; AME separated by approximately ½ their diameter, nearly touching ALE ( Figs 15, 16 ); PER recurved in dorsal view, PME oval, PLE round; PME and PLE similar in diameter; median ocular quadrangle narrower anteriorly than posteriorly, length and posterior width approximately equal. Chilum indistinct, a tiny transverse sclerite; cheliceral promargin with three teeth, separated by approximately their basal width, proximal tooth smallest, median tooth slightly larger than distal; retromargin with two subequal teeth, set close together; cheliceral escort seta present ( Figs 17, 18 ); fang with distinct serrula; endites convergent, notched laterally ( Fig. 17 ), with distinct serrula comprising sharp, ventrally curved denticles ( Fig. 19 ); dense maxillar hair tuft on mesal margins ( Figs 17–19 ); labium trapezoidal, slightly wider than long. Pleural bars sclerotised, isolated; sternum shield-shaped, longer than broad, surface smooth with deep pits without pores, sparsely covered in long straight setae ( Figs 20, 21 ); precoxal triangles present, intercoxal sclerites present between all coxal pairs. Leg formula 4123, legs I and IV often very similar in length; sparsely covered in long fine setae; femora I with mesal convex curvature, all femora strongly constricted proximally, with ventral setal bases tuberculate ( Fig. 22 ); patellar indentation on retrolateral side narrow, with lyriform organ at proximal end; anterior legs with strong paired ventral spines, chemosensory setae and trichobothria on tibiae, metatarsi and tarsi ( Figs 23–33 ); metatarsi with single long distal trichobothrium ( Fig. 29 ) and dorsal stopper ( Fig. 30 ), metatarsi III and IV with ventral preening comb at distal end; tarsi usually with single or pair of short trichobothria at 1/3 their length and long pair at 2/3 their length ( Figs 31, 32, 38 ); trichobothria with sunken distal plate, distal margin of hood overlapping plate, hood with two curved ridges, roughly concentric ( Fig. 28 ); tarsal organ oval, very slightly elevated from integument, surface finely wrinkled, opening oval and distally placed ( Fig. 39 ); paired tarsal claws short, with four intermediate teeth and moderately dense tenant setae forming claw tufts in between ( Figs 34–37 ); palpal claw simple, sharply curved distally. Abdomen oval, clearly larger in females than males, with dorsal scutum in males only; dorsum with very sparse fine setae and two pairs of sigilla, prominent in females, barely distinguishable on scutum in males ( Figs 1–12 ); abdominal markings variable, predominantly composed of cream markings forming a X on dark grey or black background ( Figs 1–12 ), sometimes reduced in O. calceata and O. marusiki sp. nov. ( Figs 70–81 ); venter without post-epigastric sclerites, with large ventral sclerite in males that is wider than long, absent in females; small, weakly sclerotised inframamillary sclerite present in females, indistinct in males. Spinnerets (details observed in O. radiata only): female ( Figs 40, 42–44 ): ALS of female with one major ampullate gland spigot and nine piriform gland spigots; PMS of female with one small minor ampullate gland spigot anteriorly and five large cylindrical gland spigots; PLS of female with two large cylindrical gland spigots anteriorly and four aciniform gland spigots posteriorly; male spinnerets ( Fig. 41 ) similarly short and stout, but spigots retracted and not examined in detail. Female epigyne with small paired CO positioned anterolaterally in epigyne ( Fig. 45 ), usually in sclerotised anterior ridges, with CD directed posteriorly towards midline (e.g. Figs 54 , 59 , 65 ); CD passing round, sclerotised bases of BU centrally; BU large, membranous, oval or teardrop-shaped, directed anterolaterally, each with small an teromesal accessory gland; short ducts connecting base of BU to transversely oval posterior ST I; fertilization ducts originating on posteromedian surface of ST I (e.g. Figs 55 , 60 ). Male palpal femur with small, finger-like RFA, with single (e.g. Fig. 63 ) or bifid (e.g. Figs 46, 47 , 58 ) tip; palpal patella without apophysis, but with retrolateral lyriform organ ( Figs 49, 50 ); palpal tibia with small triangular RTA ( Figs 48, 51 ); tegulum subtriangular, greatly expanded proximally on prolateral side, tapering distally, base nearly twice as broad as cymbium, with sperm duct running down retrolateral side of tegulum in ventral view, with single proximal loop (e.g. Fig. 57 ); embolus with broad transverse ridge at base, spike-like, with fine coils along its length ( Fig. 52 ); tegulum without any other structures.

Figures

FIGURES 13–21. Scanning electron microscope photographs of Orthobula radiata Simon, 1897 male (13–15) and female (16–21): 13. Carapace, dorsal view; 14. Detail of carapace texture, showing fine tubercles on posterior slope; 15, 16. Eye region, dorsal view; 17. Mouthparts, ventral view; 18. Right chelicera, distal view, arrow indicating promarginal escort seta; 19. Left endite, serrula; 20. Sternum, ventral view; 21. Same, details of pits and tubercles.

FIGURES 1–12. Dorsal habitus photographs of Orthobula species: 1. O. aethiopica sp. nov., female; 2. Same, male; 3. O. arca sp. nov., female; 4. Same, male; 5. O. calceata Simon, 1897, female; 6. Same, male; 7. O. marusiki sp. nov., female; 8. Same, male; 9. O. milloti Caporiacco, 1949, female; 10. Same, male; 11. O. radiata Simon, 1897, female; 12. Same, male. Scale bars: 1 mm.

FIGURES 22–30. Scanning electron microscope photographs of Orthobula radiata Simon, 1897 female (22, 24, 26) and male (23, 25, 27–30): 22. Femur I and palp, ventral view; 23. Tibia I, retrolateral view; 24. Same, ventral view; 25. Same, detail of spine; 26. Same, detail of spine bases; 27. Same, detail of chemosensory seta; 28. Same, detail of trichobothrium base; 29. Metatarsus I, retrolateral view; 30. Same, distal end, arrow indicating metatarsal stopper.

FIGURES 31–39. Scanning electron microscope photographs of Orthobula radiata Simon, 1897 male (31–35, 37) and female (36, 38, 39): 31. Tarsus I, retrolateral view; 32. Same, detail of trichobothria; 33. Same, detail of chemosensory seta; 34–36. Same, detail of tarsal claws and claw tuft in retrolateral (34), retrolateral-ventral (35) and ventral (36) views; 37. Same, detail of tips of tenent setae; 38. Tarsus III, dorsal view, black arrows indicating trichobothria and white arrow indicating tarsal organ; 39. Same, detail of tarsal organ.

FIGURES 70–81. Dorsal habitus photographs of Orthobula calceata Simon, 1897 females (70–72) and males (73–75) and O. marusiki sp. nov. females (76–78) and males (79–81), all from M’bengué, Cote d’Ivoire, indicating variation in extent of abdominal markings. Scale bars: 1 mm.

FIGURES 40–44. Scanning electron microscope photographs of Orthobula radiata Simon, 1897 female (40, 42–44) and male (41): 40, 41. Spinnerets, general view; 42. Anterior lateral spinnerets; 43. Posterior median spinnerets; 44. Posterior lateral spinnerets. Abbreviations: Ac—aciniform gland spigot; Cy—cylindrical gland spigot; mAmp—minor ampullate gland spigot; MAmp—major ampullate gland spigot; Pi—piriform gland spigot.

FIGURES 45–53. Scanning electron microscope photographs of Orthobula radiata Simon, 1897 female (45) and male (46–53): 45. Epigyne, ventral view; 46. Left palpal femur, retrolateral view; 47. Same, detail of ventrodistal apophysis; 48. Right palpal patella, tibia and tarsus, ventrolateral view; 49. Same, detail of patellar lyriform organ; 50. Same, detail of pores in lyriform organ; 51. Left palpal tibia, dorsolateral view; 52. Left embolus, retrolateral view; 53. Right embolus, retrolateral view, detail.

FIGURES 54–58. Orthobula aethiopica sp. nov., genitalic morphology of holotype female (54, 55) and paratype male (56–58) from Addis Ababa: epigyne, ventral (54) and dorsal (55) views; palp, prolateral (56), ventral (57) and retrolateral (58) views. Scale bars: 0.10 mm. Abbreviations: AG—accessory gland; BU—bursa; CD—copulatory duct; CO—copulatory opening; EM—embolus; FD—fertilisation duct; RFA—retrodistal femoral apophysis; RTA—retrolateral tibial apophysis; SBB—sclerotised base of bursa; ST I—primary spermathecae.

FIGURES 59–63. Orthobula arca sp. nov., genitalic morphology of female paratype from Bloemfontein (59, 60) and male paratype from Erfenis Dam (61–63): epigyne, ventral (59) and dorsal (60) views; palp, prolateral (61), ventral (62) and retrolateral (63) views. Scale bars: 0.10 mm.

FIGURES 65–69. Orthobula calceata Simon, 1897, genitalic morphology of female (65, 66) and male (67–69) from Bagoé: epigyne, ventral (65) and dorsal (66) views; palp, prolateral (67), ventral (68) and retrolateral (69) views. Scale bars: 0.10 mm.