Nimbarus Rollard & Wesołowska, 2002

Szűts, Tamás & Maddison, Wayne Paul, 2021, New species of the monotypic thiratoscirtine genera Ajaraneola and Nimbarus (Araneae: Salticidae: Aelurillini: Thiratoscirtina), Zootaxa 4915 (1), pp. 119-126 : 121-125

Nimbarus Rollard & Wesołowska, 2002

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Nimbarus Rollard & Wesołowska, 2002: 301 ; Maddison, Bodner & Needham, 2008: fig. 4.

Type species. N. pratensis Rollard & Wesołowska, 2002: 301 (♁ holotype, deposited in Museum National d’Histoire Naturelle [Paris]: GUINEA: Mountain Tô [07.66°N, 08.36°W], 1600-1650 m a.s.l., leg. M. Lamotte & R. Roy, 12–13.XII.1951 [meadow] – not examined). By original designation.

Remark. An apparent third species was mentioned and figured by Maddison et al. (2008: fig. 4), sharing with the other Nimbarus species the triangular process (tp) and the tight curve of the embolus, and the small hook-shaped RTA.

Diagnosis. Males can be recognized by the process(es) of the tegulum prolateral to the embolar base ( Figs 13, 18 , marked with tp; visible in fig. 14C only of Rollard & Wesołowska 2002; Maddison et al. 2008: fig. 4), the medium to long-sized (as long as the diameter of the tegulum) flat embolus. A characteristic ledge is present on the retrolateral side of the palpal tibia ( Figs 13, 19 , marked with trl), similar to a structure that is found in a few Thiratoscirtus Simon, 1886 species ( T. torquatus Simon, 1903 , T. fuscorufescens Strand, 1906 , T. minimus Dawidowicz & Wesołowska, 2016 and T. capito Simon, 1903 ). In Bodner and Maddison’s analyses (2012), Thiratoscirtus species ‘brown’, ‘band’, and ‘long cymbium’ all possess this feature, with a row of long modified setae on the ledge. Whether the retrolateral ledge is homologous or convergent in these cases is unclear. Nimbarus can be differentiated from those Thiratoscirtus by the modified setae being thin, and not thick.

Members of the genus are similar to Longarenus in overall appearance (~ 4 mm in size, high and quadrangular carapace as seen from the lateral side, see e.g. Szűts 2007) and copulatory organ morphology, but in addition to the characters above, they can be distinguished by the lack of a band of white setae circling the sides and back of the thorax above the margin ( N. nimbus has an V-shaped white band originating and ending in PLEs, but not present on the side of the carapace), in having a triangular-shaped process on the tegulum (lacking in Longarenus , but with a process on the embolus base instead), and in having a unident retrolateral tooth on the chelicera (fissident in Longarenus ).

Description. For full description see Rollard & Wesłowska 2002. Small (less than 4 mm), unidentate thiratoscirtines, with high carapace (more than 75% of carapace length see Fig. 17 ; Rollard & Wesołowska 2002: fig. 14A) and white clypeal setae. Prolateral to the embolus is a more-or-less triangular process ( Figs 13, 18 , tp). Males of this genus have a medium-sized, flattened embolus, and small hook-shaped RTA ( Figs 13–15 ).

Distribution. Known from Guinea, Ghana and Cameroon ( Fig. 21 ).

Nimbarus nimbus sp. nov.

[ urn:lsid:zoobank.org:act:EC8145A6-97D7-4294-9B9A-9C397447DF95

Figs 13–20

Type material. Holotype ♁: CAMEROON: Southwest Prov. , Fako Div., Limbe subdiv., 1.4 km NE of Etome, 04.05°N, 09.125°E, 400 m a.s.l., leg. Larcher, Hormiga, Coddington, Griswold & Wanzie, 13–19.I.1992 ( CAS, CASENT 9050508 ).

Etymology. Named in honor of Wanda Wesołowska, for her contributions to the taxonomy of thiratoscirtines. The species epithet is a Latin noun in apposition ( nimbus means aureole, earned respect).

Diagnosis. The species can be differentiated from Nimbarus pratensis and Nimbarus sp. ( Maddison et al. 2008: fig. 4) by lacking a long (as long as half of the cymbium’s length) DTA. However, a distinctive outgrowth on the prolateral side of the palpal tibia is present. Female: Unknown.

Description. Male (CAS, CASENT 9050508). Carapace length 1.5; abdomen length 1.2; femur III 1.10; patella + tibia III 1.21; femur IV 0.95; patella + tibia IV 0.9. Carapace light brown, almost yellowish, ocular area slightly darker, with orange setae ( Fig. 16 ). Thoracic area with fringe of short stiff white setae forming “V”, ending at PLEs ( Fig. 16 ). Carapace high, thoracic slope steep ( Fig. 17 ), but less abrupt than in Longarenus ( Szűts 2007) . Clypeus dark brown, with row of white setae ( Fig. 17 ). Chelicerae brown and vertical, with unident tooth. Legs dark brown, with some lighter patches; distal segments significantly lighter in color. First tibia with 3 pairs of ventral macrosetae. Abdomen in alcohol light yellow on venter, dark on dorsum, with wide median stripe. Palp light brown. Tibia with small retrolateral hook-shaped RTA, with retrolateral tibial ledge (trl on Fig. 19 ), and with prolateral bulge ( Fig. 15 ). Embolus medium in length, flattened and with tight clockwise bend ( Figs 13, 18 ); tegulum with few darker spots, with prolateral triangular paler process (tp on Fig. 18 ).

Distribution. Only known from the type locality in Cameroon.

Comments. Our assignment of this species to Nimbarus is tentative. However, as mentioned by Rollard and Wesołowska (2002): “ relationships of this genus are difficult to settle ”. By describing this species here and offering hypotheses for delimiting characters (i.e. the small body size, high carapace and the triangular tegular process), we hope to stimulate further exploration of this genus.

Figures

FIGURE 21. Map of central Africa showing geographical locations of specimens studied (based on public domain image from NASA/JPL/NIMA).

FIGURES 13–20. Nimbarus nimbus sp. nov. (male holotype). 13–15 Palp ventral, dorsal and retrolateral views. 16–17. Habitus in alcohol, dorsal and lateral. 18–20 Palp photographs, ventral, retrolateral and dorsal views. Scale bars = 1.0 mm (16–17), 0.1 mm (13–15, 18–20).