Orthobula arca, Haddad & Jin & Platnick, 2022

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 : 364-367

Orthobula arca sp. nov.

Figs 3, 4 , 59–63

Diagnosis. Females of O. arca sp. nov. can be easily recognized from congeners by the large arch-shaped anterior ridge, with lateral extensions flanking the CO ( Fig. 59 ). Males can be easily distinguished from congeners by the distinct bend of the embolus at approximately 2/3 its length ( Figs 61–63 ).

Etymology. From the Latin for “arch”, referring to the shape of the anterior margin of the epigynal atrium.

Female (holotype, Deelhoek, NCA 2021/1248). Measurements: CL 0.93, CW 0.70, AL 1.03, AW 0.79, TL 2.00 (1.60–2.30), PERW 0.29, MOQAW 0.12, MOQPW 0.17, MOQL 0.14. Length of leg segments: I 0.59 + 0.22 + 0.51 + 0.44 + 0.27 = 2.03; II 0.51 + 0.21 + 0.38 + 0.38 + 0.25 = 1.73; III 0.42 + 0.20 + 0.30 + 0.35 + 0.22 = 1.49; IV 0.56 + 0.22 + 0.47 + 0.52 + 0.29 = 2.06.

Colour: carapace orange-brown, with mottled black margins and faint black mottled patch centrally; chelicerae yellow-brown; endites and labium yellow-brown, cream distally; sternum yellow-orange, with yellow-brown margins; palps yellow-brown; legs with femora, patellae and tibiae yellow-brown, other leg segments yellow; patellae and tibiae I with black mottling dorsally and laterally, on II–IV on retrolateral side only; abdomen dark grey dorsally, with pair of cream longitudinal patches anterolaterally and oblique cream markings at midpoint, merging medially to form X; venter cream, with faint mottling on epigastric plate, faint mottled grey patch in front of spinnerets; spinnerets cream.

Leg spination: femora and patellae: spineless; tibiae: I plv 6 rlv 5, II plv 5 rlv 4; metatarsi: I plv 4 rlv 4, II plv 4 rlv 4; tarsi: I plv 3 rlv 3, II plv 3 rlv 3.

Epigyne with lateral CO in broad arch-shaped epigynal ridge, with posterolateral extensions ( Fig. 59 ); CO short, directed posteriorly, entering round SBB at centre of epigyne; CD approximately same length as width of SBB; SBB separated by slightly less than their width; BU subtriangular, with boomerang-shaped accessory gland on their anteromesal surface; SBB connected to ST I by short looping ducts, entering broad, transversely oval ST I on their mesal surface ( Fig. 60 ).

Male (paratype, Erfenis Dam Nature Reserve, NCA 2009/3636). Measurements: CL 0.81, CW 0.64, AL 0.68, AW 0.58, TL 1.53 (1.46–1.70), PERW 0.26, MOQAW 0.10, MOQPW 0.14, MOQL 0.13. Length of leg segments: I 0.47 + 0.18 + 0.40 + 0.35 + 0.23 = 1.63; II 0.44 + 0.17 + 0.33 + 0.32 + 0.23 = 1.49; III 0.37 + 0.17 + 0.25 + 0.29 + 0.19 = 1.17; IV 0.51 + 0.18 + 0.41 + 0.44 + 0.25 = 1.79.

Colour: carapace orange-brown, with mottled black margins and indistinct black mottled patch centrally; chelicerae yellow-brown; endites and labium yellow-brown, cream distally, labium darker in proximal half; sternum yellow-orange, with yellow-brown margins and faint black mottling; palps yellow-brown; legs with femora, patellae and tibiae yellow-brown, other leg segments yellow; patellae and tibiae I with black mottling dorsally and laterally, on II–IV on retrolateral side only; abdomen black dorsally, with pair of cream subtriangular patches anterolaterally and transverse cream band at midpoint, latter slightly projecting anteriorly along midline; venter cream, with small mottled grey patch in front of spinnerets; spinnerets cream.

Leg spination: femora and patellae: spineless; tibiae: I plv 5 rlv 5, II plv 4 rlv 4; metatarsi: I plv 4 rlv 4, II plv 4 rlv 4; tarsi: I plv 3 rlv 3, II plv 3 rlv 3.

Palpal femur with small, finger-like, curved RFA ( Fig. 63 ); tibia with small, simple triangular apophysis; retrodistal tegular ridge weakly developed, restricted to retrolateral surface, not curving around ventrally to base of embolus ( Figs 62, 63 ); basal section of embolus leaning slightly prolaterally, with distinct bend at 2/3 its length, tip directed slightly retrolaterally ( Figs 61–63 ).

Type material. Holotype ♀: SOUTH AFRICA: Free State: Bloemfontein district, Deelhoek farm, 28°51’S, 26°07’E, 1265 m a.s.l., 17.XI.2001, leg. C. Haddad ( Eucalyptus leaf litter) ( NCA 2021 /1248).

Paratypes: SOUTH AFRICA: Free State: Benfontein Nature Reserve, 28°50.452’S, 24°49.473’E, 13.III.2010, leg. C. Haddad (base of grass tussocks), 2♂ 2♀ ( NCA 2010 /317); Bethulie district, Tussen-die-Riviere Nature Reserve , 30°29’S, 26°11’E, 15.X.2008, leg. L. Lotz & C. Haddad (under rocks, riparian woodland edge), 1♀ ( NMBA 12755 ); Bloemfontein district , Hopefield farm, 28°52.949’S, 26°09.336’E, 1290 m a.s.l., 11.XI.2001, leg. C. Haddad (sweepnetting, Eragrostis grass), 1♀ ( NCA 2021 /1246); Bloemfontein district , Deelhoek farm, 28°51’S, 26°07’E, 1265 m a.s.l., 21.X.2001, leg. C. Haddad (sweeps, Themeda grassland), 1♀ (MHBU) ; Bloemfontein, Free State National Botanical Gardens , 29°02.892’S, 26°12.662’E, 1390 m a.s.l., 26.II–13.III.2011, leg. J.A. Neethling (pitfalls, open grassland), 4♂ 6♀ (MHBU) ; Brandfort district, Florisbad Research Station, 28°46’S, 26°05’E, 1250 m a.s.l., 8.XII.1987, leg. L.N. Lotz (pitfall traps), 1♀ ( NMBA 8627 ); Erfenis Dam Nature Reserve , Site 1, 28°28.892’S, 26°48.508’E, 31.VIII–30.IX.2009, leg. R. Fourie & A. Grobler (pitfall traps, grassland near trench), 1♂ ( NCA 2009 /3636); Kroonstad district , Koffielaagte farm, 27°29’S, 27°28’E, 1425 m a.s.l., 4.I.2002, leg. C. Haddad (sweeps in grassland), 1♀ ( NCA 2021 /1247) .

Other material examined. SOUTH AFRICA: Free State: Amanzi Private Game Reserve , 28°35.845’S, 26°26.280’E, 1–30.IX.2012, leg. V. Butler (pitfall traps, open grassland), 1♀ ( NCA 2013 /3355) ; Same locality, 28°36.365’S, 26°25.030’E, 1–30.IV.2013, leg. V. Butler (pitfall traps, Acacia karroo woodland), 1♂ 3♀ ( NCA 2013 /3551) ; Same locality, 28°35.430’S, 26°26.290’E, 1–31.I.2013,leg. V. Butler (pitfall traps, vegetation around dam), 1♂ ( NCA 2013 /4307) ; Same locality, 28°36.722’S, 26°26.148’E, 24.XI.2013 – 20.I.2014, leg. C. Haddad & V. Butler (pitfalls, open woodland), 1♂ ( NCA 2014 /1077) ; Same locality, 28°36.712’S, 26°26.186’E, 1450 m a.s.l., 10.X.2017, leg. C. Haddad (base of grass tussocks), 1♀ ( NCA 2017 /933) ; Same locality, 28°35’S, 26°25’E, 19–23.I.2014, leg. AFRAS colloquium delegates, 1♀ ( NCA 2014 /1028) ; Bloemfontein , Free State National Botanical Gardens , 29°02.892’S, 26°12.662’E, 1390 m a.s.l., 24.IX–8.X.2009, leg. C. Haddad (pitfalls, Rhus lancea woodland), 1♀ ( NCA 2009 /3490) ; Same locality, 27.X–16.XI.2009, leg. C. Haddad (pitfall traps), 1♀ ( NMBA 13989 ) ; Same locality, 9.XII.2009 – 4.I.2010, leg. C. Haddad (pitfall traps, grassland), 1♂ 1♀ ( NMBA 15103 ) , 3♂ 7♀ ( NMBA 15024 ) ; Same locality, 20.X–9.XI.2013, leg. C. Haddad (open pitfalls, grassland), 3♂ 3♀ ( NCA 2017 /1555) ; Same locality, XII.2014, leg. C. Haddad (open pitfalls, grassland), 2♀ ( NCA 2015 /1845) ; Same locality, VI.2016, leg. C. Haddad & L. Whitehead ( Hyparrhenia hirta grass tussocks), 1♀ ( NCA 2016 /3060) ; Erfenis Dam Nature Reserve, Site 1, 28°28.892’S, 26°48.508’E, 30.IX–28.X.2009, leg. R. Fourie & A. Grobler (pitfall traps, grassland near trench), 3♀ ( NCA 2009 /3579), 1♀ ( NMBA 14359 ) ; Erfenis Dam Nature Reserve, Site 8, 28°29.804’S, 26°48.503’E, 31.VIII–30.IX.2009, leg. R. Fourie & A. Grobler (pitfall traps, Themeda grassland), 3♀ ( NCA 2009 /3655) ; Same data but 30.IX–28.X.2009, 1♀ ( NCA 2009 /3604), 2♀ ( NMBA 14485 ) ; Erfenis Dam Nature Reserve, Burned site 1, 28°30.373’S, 26°48.437’E, 21.IX–22.X.2005, leg. C. Haddad, S. Otto & R. Poller (pitfall traps, grassland), 1♀ ( NMBA 13923 ) ; Same data but 22.X–22.XI.2005, leg. C. Haddad, S. Otto & R. Poller, 3♀ ( NMBA 13924 ) ; Same data but 23.XII.2005 – 23.I.2006, leg. C. Haddad, 1♂ 1♀ ( NMBA 13925 ) ; Same data but 24.II–27.III.2006, leg. S. Otto & R. Poller, 3♂ ( NMBA 13926 ) ; Same data but 27.III–28.IV.2006, leg. C. Haddad & R. Lyle, 1♂ 1♀ ( NMBA 13927 ) ; Same data but 28.IV–26.V.2006, leg. C. Haddad & R. Lyle, 3♀ ( NMBA 13928 ) ; Same data but 26.V–28.VI.2006, leg. S. Otto & R. Poller, 1♂ 1♀ ( NMBA 13929 ) ; Same data but 28.VI–28.VII.2006, leg. C. Haddad & R. Lyle, 1♂ ( NMBA 13930 ) ; Erfenis Dam Nature Reserve, Burned site 2, 28°30.134’S, 26°48.427’E, 22.X–22.XI.2005, leg. C. Haddad, S. Otto & R. Poller (pitfall traps, grassland), 1♂ 1♀ ( NMBA 13931 ) ; Same data but 27.III–28.IV.2006, leg. C. Haddad & R. Lyle, 1♀ ( NMBA 13933 ) ; Same data but 28.IV–26.V.2006, leg. C. Haddad & R. Lyle, 1♀ ( NMBA 13932 ) ; Erfenis Dam Nature Reserve, Burned site 3, 28°29.990’S, 26°48.486’E, 21.IX–22.X.2005, leg. C. Haddad, S. Otto & R. Poller, 1♀ ( NMBA 13935 ) ; Same data but 22.X–22.XI.2005, leg. C. Haddad, S. Otto & R. Poller (pitfall traps, grassland), 2 imm. 4♂ ( NMBA 13934 ) ; Same data but 23.XII.2005 – 23.I.2006, leg. C. Haddad, S. Otto & R. Poller, 2♂ ( NMBA 13936 ) ; Same data but 24.I–24.II.2006, leg. C. Haddad & R. Lyle, 1♂ ( NMBA 13937 ) ; Same data but 24.II–27.III.2006, leg. S. Otto & R. Poller, 5♀ ( NMBA 13938 ) ; Same data but 27.III–28.IV.2006, leg. C. Haddad & R. Lyle, 5♂ 5♀ ( NMBA 13939 ) ; Same data but 28.IV–26.V.2006, leg. C. Haddad & R. Lyle, 1 imm. 2♂ 6♀ ( NMBA 13940 ) ; Same data but 28.VII–1.IX.2006, leg. C. Haddad, S. Otto & R. Poller, 1♂ 1♀ ( NMBA 13941 ) ; Erfenis Dam Nature Reserve, Unburned site 1, 28°29.888’S, 26°48.488’E, 21.IX–22.X.2005, leg. C. Haddad, S. Otto & R. Poller (pitfall traps, grassland), 1♂ ( NMBA 13900 ) ; Same data but 22.X–22.XI.2005, leg. C. Haddad, S. Otto & R. Poller, 2 imm. 2♂ 2♀ ( NMBA 13901 ) ; Same data but 22.XI– 23.XII.2005, leg. C. Haddad, 11♂ 7♀ ( NMBA 13902 ) ; Same data but 23.XII.2005 – 23.I.2006, leg. C. Haddad, S. Otto & R. Poller, 6♂ 3♀ ( NMBA 13903 ) ; Same data but 23.I–24.II.2006, leg. C. Haddad & R. Lyle, 4♂ 2♀ ( NMBA 13904 ) ; Same data but 24.II–27.III.2006, leg. S. Otto & R. Poller, 2 imm. 5♂ 3♀ ( NMBA 13905 ) ; Same data but 27.III–28.IV.2006, leg. C. Haddad & R. Lyle, 1 imm. 1♀ ( NMBA 13906 ) ; Same data but 28.IV–26.V.2006, leg. C. Haddad & R. Lyle, 1♂ 2♀ ( NMBA 13907 ) ; Erfenis Dam Nature Reserve, Unburned site 2, 28°29.706’S, 26°48.281’E, 21.IX–22.X.2005, leg. C. Haddad, S. Otto & R. Poller (pitfall traps, grassland), 2♂ 1♀ ( NMBA 13908 ) ; Same data but 22.X–22.XI.2005, leg. C. Haddad, S. Otto & R. Poller, 1 imm. 4♂ 2♀ ( NMBA 13909 ) ; Same data but 22.XI–23.XII.2005, leg. C. Haddad, 2♂ 2♀ ( NMBA 13910 ) ; Same data but 23.XII.2005 – 23.I.2006, leg. C. Haddad, S. Otto & R. Poller, 1 imm. 3♂ 4♀ ( NMBA 13911 ) ; Same data but 24.II–27.III.2006, leg. S. Otto & R. Poller, 2♂ ( NMBA 13912 ) ; Same data but 27.III–28.IV.2006, leg. C. Haddad & R. Lyle, 7♂ 5♀ ( NMBA 13913 ) ; Same data but 28.IV–26.V.2006, leg. C. Haddad & R. Lyle, 6♂ 2♀ ( NMBA 13914 ) ; Same data but 1–30.IX.2006, leg. C. Haddad, S. Otto & R. Poller, 1♂ ( NMBA 13915 ) ; Erfenis Dam Nature Reserve, Unburned site 3, 28°29.741’S, 26°48.065’E, 22.XI–23.XII.2005, leg. C. Haddad (pitfall traps, grassland), 6♂ 6♀ ( NMBA 13916 ) ; Same data but 23.XII.2005 – 23.I.2006, leg. C. Haddad, S. Otto & R. Poller, 1♂ 1♀ ( NMBA 13917 ) ; Same data but 23.I–24.II.2006, leg. C. Haddad & R. Lyle, 2♀ ( NMBA 13918 ) ; Same data but 24.II–27.III.2006, leg. S. Otto & R. Poller, 5♂ 2♀ ( NMBA 13919 ) ; Same data but 27.III–28.IV.2006, leg. C. Haddad & R. Lyle, 2♂ 3♀ ( NMBA 13920 ) ; Same data but 28.IV–26.V.2006, leg. C. Haddad & R. Lyle, 2♂ 2♀ ( NMBA 13921 ) ; Same data but 1–30.IX.2006, leg. C. Haddad, S. Otto & R. Poller, 1♀ ( NMBA 13922 ) ; Sandveld Nature Reserve , 27°44.043’S, 25°45.805’E, 2–30.X.2009, leg. R. Fourie & A. Grobler (pitfall traps, grassland), 4♀ ( NCA 2009 /3566) ; Same locality, 2.IX–2.X.2009, leg. R. Fourie & A. Grobler (pitfall traps, grassland), 1♀ ( NMBA 15107 ) . Gauteng: Johannesburg, Roodepoort, Ruimsig , 26°08’S, 27°51’E, 20.V.2000, leg. A. Leroy (in house), 1♀ ( NCA 2007 /3834) ; Pretoria, Rietondale Research Campus , 25°43.780’S, 28°13.862’E, 16.VII.1998, leg. J. Nkwana (pitfall traps), 1♂ ( NCA 2007 /1151) . KwaZulu-Natal: Sani Pass Elevational Transect , 30°11’00.6’’S, 30°09’07.8’’E, 900 m a.s.l. (8a), leg. University of Pretoria students (pitfall traps), 1♀ ( NCA 2011 /774) ; Sani Pass , 29°39’S, 29°27’E, IX.2006, leg. D. Prentice (pitfall traps), 1♀ ( NCA 2008 /1982) .

Habitat and biology. This species was regularly collected from pitfall traps in the Grassland Biome of central South Africa. In contrast with its congeners, this species was far more abundant in open grasslands (3.8 %; Haddad et al. 2015) than in leaf litter (absent in Butler & Haddad 2011; Haddad et al. 2019) or shrubland habitats (0.13 %; Haddad & Butler 2018). On rare occasions, it was collected by sweeping grass (e.g. Haddad 2005).

In a study investigating the impacts of controlled burning in central South African grasslands ( Haddad et al. 2015), 180 adult O. arca sp. nov. were collected from the Erfenis Dam Nature Reserve. The proportion of males (n = 92) to females (n = 88) was almost identical. Considering its dominance as a component of Corinnidae (n = 234) in the study (its placement at the time), it likely contributed to the observed significant impact of fire on this family, as 126 individuals were sampled from the three unburnt control sites compared to only 54 individuals sampled at the three burnt sites. Regarding adult phenology ( Fig. 64 ), the species occurred throughout the year, but was most common from late spring to late autumn, and was rare during winter.

Distribution. Widespread in the Grassland Biome of central South Africa ( Fig. 82 ).

Figures

FIGURE 64. Phenology of adult Orthobula arca sp. nov. in a year-long pitfall trapping study conducted at the Erfenis Dam Nature Reserve, South Africa (see Haddad et al. 2015).

FIGURE 82. Distribution of Orthobula aethiopica sp. nov. (circles), O. arca sp. nov. (squares) and O. calceata Simon, 1897 (triangles) in the continental Afrotropical Region.

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 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.