Trachelas L. Koch, 1872

Trachelas L. Koch, 1872 View in CoL

Trachelas L. Koch, 1872: 256 View in CoL ; O. Pickard-Cambridge 1872: 256; Chickering 1972: 215; Platnick & Shadab 1974a: 1; Platnick & Shadab 1974b: 1; Platnick 1975: 1; Paik 1991: 198; Deeleman-Reinhold 2001: 393; Bosselaers et al. 2009: 16; Zhang et al. 2009: 41 View Cited Treatment ; Jin et al. 2017: 46.

Type species: Trachelas minor O. Pickard-Cambridge, 1872 , by original designation.

Remarks. The name Trachelas was first used by L. Koch (1866) in an identification key, but as no type species had been described in the genus, it was considered a nomen nudum. Subsequently, O. Pickard-Cambridge (1872) described Trachelas minor , formalizing the recognition of the genus. L. Koch (1872) provided a more detailed description of the genus, with its authorship being attributed to him.

Diagnosis. Trachelas sensu stricto differs from other Afrotropical genera that lack leg spines and ventral cusps on the anterior legs in males, i.e. Coronarachne Haddad & Lyle, 2024 , Falcaranea Haddad & Lyle, 2024 , Fuchiba Haddad & Lyle, 2008 , Fuchibotulus Haddad & Lyle, 2008 , Mushimane Haddad, 2025 and Trachycymbius Haddad & Lyle, 2024, by the very coarse carapace integument (shared with Fuchiba and Fuchibotulus ), the presence of a male palpal patellar apophysis and the absence of a tibial apophysis (except T. scutatus sp. nov.), and by the distinct, sclerotized oval atria or curved ridges of the epigyne that are situated close to the midline.

Description ( Trachelas sensu stricto). Small spiders, 1.76–4.72 mm in length; carapace bright yellow to deep red-brown; oval, broadest at coxae II, gradually narrowed towards eye region ( Figs 1A, F View FIGURE 1 , 2A View FIGURE 2 , 6 View FIGURE 6 , 7 View FIGURE 7 ); fovea distinct, a short broad slit; posterior margin distinctly concave ( Figs 6 View FIGURE 6 , 7 View FIGURE 7 ); convex in lateral profile, strongly elevated from clypeus to approximately 1/3 carapace length, slightly convex in midsection, with steeper slope in posterior 1/3 ( Fig. 1B, G View FIGURE 1 ); carapace surface coarsely granulate, with each seta accompanied by posterior transverse ridge and pair of deep depressions ( Fig. 2B View FIGURE 2 ). All eyes surrounded by black rings; AER procurved in anterior view ( Fig. 2C View FIGURE 2 ), slightly recurved in dorsal view ( Fig. 2D View FIGURE 2 ); clypeus usually slightly smaller to slightly larger than AME diameter at AME, AME very slightly larger than ALE; PER slightly recurved in dorsal view ( Fig. 2D View FIGURE 2 ); PLE usually very slightly larger than PME; MOQ narrower anteriorly than posteriorly, posterior width slightly larger than length. Chilum absent; cheliceral promargin with three teeth ( Fig. 2E View FIGURE 2 ), retromargin with two teeth, usually on common base ( Fig. 2F View FIGURE 2 ); fang with distinct serrula ( Fig. 2F View FIGURE 2 ); posterior surface of paturon with field of long setae, single modified short seta and field of pores posterior to retromarginal teeth ( Fig. 2G, H View FIGURE 2 ); endites converging slightly distally, lateral margins not parallel, mesal margins with longitudinal groove and dense maxillar hair tuft ( Fig. 2I View FIGURE 2 ), distal margins with distinct serrula comprising elongate denticles with sharp tips ( Fig. 2J View FIGURE 2 ); labium trapezoidal, narrower distally than proximally, length less than proximal width, distal margin with slight concavity ( Fig. 2I View FIGURE 2 ). Pleural bars sclerotised, isolated ( Fig. 1G View FIGURE 1 ); sternum shield-shaped, slightly longer than broad, broadest at coxa II ( Fig. 1C, H View FIGURE 1 ), surface smooth centrally, covered in long straight setae with more pronounced tuberculate bases towards borders ( Fig. 2K View FIGURE 2 ); precoxal triangles present, intercoxal sclerites short but usually present between all coxal pairs. Leg formula 4123 or 1423, sparsely covered in fine setae ( Fig. 3B–K View FIGURE 3 ); leg I and II only slightly thickened compared to legs III and IV ( Figs 1A–C, F–H View FIGURE 1 , 6 View FIGURE 6 , 7 View FIGURE 7 ); dorsal femoral surface almost straight, very slightly concave at ½ its length, ventral surface very slightly convex ( Fig. 1D, I View FIGURE 1 ); all femora strongly constricted proximally ( Fig. 1D, I View FIGURE 1 ); patellar indentation on retrolateral side narrow, with lyriform organ at proximal end ( Fig. 3B, C View FIGURE 3 ); legs I and II of both sexes without ventral cusps on tibiae, metatarsi or tarsi, only with weak scopulae ( Fig. 3D–K View FIGURE 3 ); all tibiae, metatarsi and tarsi with sparse dorsal trichobothria ( Fig. 3H, I View FIGURE 3 , 4B, C View FIGURE 4 ); metatarsi with short metatarsal stopper ( Figs 3J, K View FIGURE 3 , 4A View FIGURE 4 ), metatarsi III and IV with weak ventral preening brush and comb at distal end ( Figs 3F View FIGURE 3 , 4A View FIGURE 4 ); tarsi with sparse tactile hairs, few dorsal trichobothria and chemosensory setae ( Fig. 3G, K View FIGURE 3 ); trichobothria with slightly lowered distal plate, distal margin of hood overlapping plate, hood with four to six roughly concentric curved ridges ( Fig. 4B, C View FIGURE 4 ); tarsal organ at approximately 4/5 tarsus length ( Fig. 3K View FIGURE 3 ), flush with integument, surface finely wrinkled, opening oval and distally placed ( Fig. 4D View FIGURE 4 ); paired tarsal claws short, with eight teeth and dense tenant setae forming claw tufts in between ( Figs 3G, K View FIGURE 3 , 4E, F View FIGURE 4 ). Abdomen oval, sometimes uniformly coloured, otherwise with mottled grey markings or chevrons on creamy-grey background ( Figs 1A–C, F–H View FIGURE 1 , 6 View FIGURE 6 , 7 View FIGURE 7 ); dorsal scutum usually in males only, only in female of T. scutatus sp. nov. ( Fig. 7E View FIGURE 7 ), covering most of dorsum; dorsum covered in scattered short fine setae, with two pairs of sigilla in both sexes; venter without large sclerites, with paired rows of indistinct tiny sclerites from epigastric furrow to spinnerets, covered in scattered short fine setae ( Fig. 1C, H View FIGURE 1 ). Spinnerets short, conical, in compact group, spigots only studied in detail in both sexes of T. canariensis : ALS of males with one MAmp, six Pi, a single Nu and single Ta ( Fig. 4G View FIGURE 4 ), of females with one MAmp, seven Pi and single Ta ( Fig. 4J View FIGURE 4 ); PMS of males only with single mAmp and five Ac ( Fig. 4H View FIGURE 4 ), of females with one mAmp, four Cy and six Ac ( Fig. 4K View FIGURE 4 ); PLS of males with one mAmp and six Ac ( Fig. 4I View FIGURE 4 ), of females with two Cy and seven Ac ( Fig. 4L View FIGURE 4 ). Male palpal femur with distinct distal ventral concavity ( Fig. 5A View FIGURE 5 ; see also Bosselaers et al. 2009: fig. 4; Jin et al. 2017: fig. 3D); patella with triangular or hook-like retrolateral PA, with ventral patellar indentation with lyriform organ at its base ( Fig. 5B–E View FIGURE 5 ); palpal tibiae without apophyses (except T. scutatus sp. nov., with rounded RTA), sometimes only with distal retrolateral sclerotized ridge; TE generally oval in ventral view, as broad as CY, with distinct distal TA ( Fig. 5E View FIGURE 5 ); EM base broad, originating prodistally or distally, EM forming simple distal coil or loop ( Fig. 5E View FIGURE 5 ). Female palpal claw simple, slightly bent distally, without teeth ( Fig. 2A View FIGURE 2 ). Epigyne quite heavily sclerotized, with CO in oval AT or curved ridges near midline in anterior half ( Fig. 5F View FIGURE 5 ), without hood; CD usually directed anteriorly, often looping, with terminal swelling with narrow stalk entering almost round ST II near centre (see Ramírez 2014: fig. 179D) [ST II often break off during ultrasonic cleaning of epigyne]; Cd usually looping before running posteriorly near midline of epigyne before entering oval or bilobed posterior or posterolateral ST I; Cd usually with thickened section prior to entering ST I.

Composition. Based on the current study and a review of the literature, the following species should be considered as Trachelas sensu stricto: T. canariensis Wunderlich, 1987 (Canary Islands, Spain, and East, Central and southern Africa), T. chamoli Quasin, Siliwal & Uniyal, 2018 ( India), T. chubbi Lessert, 1921 (Central and East Africa), T. costatus O. Pickard-Cambridge, 1885 ( Pakistan and India), T. crewsae Marusik & Fomichev, 2020 ( Tajikistan), T. falsus sp. nov. (Central, West and southern Africa), T. himalayensis Biswas, 1993 ( India), T. humus sp. nov. (southern Africa), T. leggi sp. nov. ( South Africa), T. longinquus sp. nov. ( Central African Republic), T. minor O. Pickard-Cambridge, 1872 (Europe, West Asia, North Africa), T. oreophilus Simon, 1906 ( India and Sri Lanka), T. pusillus Lessert, 1923 (Central and southern Africa), T. quisquiliarum Simon, 1906 ( Sri Lanka), T. russellsmithi sp. nov. ( Ethiopia), T. scutatus sp. nov. ( Ghana and Nigeria), T. smithi sp. nov. ( Kenya), T. sylvae Caporiacco, 1949 (Central and East Africa), T. tanasevitchi Marusik & Kovblyuk, 2010 (far eastern Russia), T. uniaculeatus Schmidt, 1956 (Canary Islands) and T. vulcani Simon, 1896 ( China, Indonesia and Japan).

The New World fauna, currently including 62 described species ( World Spider Catalog 2025), represents a phylogenetically distinct lineage from Trachelas sensu stricto ( Fig. 23 View FIGURE 23 ; Pett et al. unpublished data) and is thus not considered further here. Several Asian species, i.e. the Chinese T. alticolus Hu, 2001 , T. bomiensis Jin & Mi, 2024 ( Liu et al. 2024), T. brachialis Jin, Yin & Zhang, 2017 , T. gaoligongensis Jin, Yin & Zhang, 2017 , T. gigapophysis Jin, Yin & Zhang, 2017 , T. nanyueensis Yin, 2012 ( Yin et al. 2012) and T. sinensis Chen, Peng & Zhao, 1995 , as well as T. japonicus Bösenberg & Strand, 1906 from far eastern Russia, China, Japan and Korea, are likely misplaced and may belong to a new genus. Males of most of these species have ventral cusps on the anterior legs (except T. alticola and T. sinensis , apparently absent, and T. nanyuensis , not indicated in description) and a well-developed palpal tibial apophysis (often basal and posteriorly directed). Their females have an epigyne with a very different internal structure to Trachelas sensu stricto, particularly the usually elongate lateral ST II (more oval in T. japonicus ) and long connecting ducts originating laterally, curving in an arch mesally then posteriorly (e.g. Zhang et al. 2009; Yin et al. 2012; Jin et al. 2017; Jin & Mi 2024; Tang et al. 2024). Furthermore, the Chinese T. fanjingshan Zhang, Fu & Zhu, 2009 , T. fasciae Zhang, Fu & Zhu, 2009 , T. kavanaughi Tang, Yan, Zhao & Peng, 2024 , T. shilinensis Jin, Yin & Zhang, 2017 , T. ventriosus Tang, Yan, Zhao & Peng, 2024 and T. zhui Li, Wang, Zhang & Chen, 2019 , all known only from females, have a similar internal epigyne structure to that of the Asian species referred to above and are thus also likely to be misplaced, but confirmation of this requires discovery of their males. Trachelas devi Biswas & Raychaudhuri, 2000 ( Bangladesh) has a procurved PER and very different somatic morphology and genitalia to Trachelas sensu stricto ( Biswas & Raychaudhuri 2000: figs 15–21), so is likely not a trachelid and should be transferred to another family.