Afromygale, Zonstein, 2020

Zonstein, Sergei L., 2020, On Afromygale, a new mygalomorph spider genus from East Africa (Araneae: Pycnothelidae), Israel Journal of Entomology (Oxford, England) 50 (1), pp. 131-146 : 133-135

Genus Afromygale n. gen.

LSID: urn:lsid:zoobank.org:act:501CAA13­6CCD­403E­933C­7DF46ADBD12E .

Type species: Afromygale rukanga n. sp., by present designation.

Etymology: Afromygale is a combination of the Latinized prefix Afro ­ (that means African) and the historical genus name Mygale used in the first half of XIX century for most mygalomorph species known at that time (later, Mygale Latreille, 1802 in the Araneae was found to be preoccupied by Mygale Cuvier, 1800 in the Mammalia and replaced by Avicularia Lamarck, 1818 ); the gender is feminine.

Diagnosis: A controversial set of the diagnostic characters found in members of Afromygale n. gen. could indicate their similarity to several mygalomorph families (see Discussion). Nevertheless, the genus can be easily distinguished from all other groups of African mygalomorphs where spiders are known to possess tarsi I–IV provided with the biserially toothed paired claws and lacking tarsal tufts:

(a) from the Cyrtaucheniidae ( Cyrtauchenius Thorell, 1869 , Acontius Karsch, 1879 and Ancylotrypa Simon, 1889 ) – by a well defined and highly elevated eye tubercle, by a short and straight thoracic fovea and by the absence of a true cheliceral rastellum;

(b) from the Entypesidae ( Hermacha Simon, 1889 , Entypesa Simon, 1902 and Lepthercus Purcell, 1902 ) – by a considerably shorter apical segment of PLS (triangular vs. digitiform) and by the absence of the metatarsal preening combs;

(c) from the Bemmeridae ( Spiroctenus Simon, 1889 , where males possess teeth on the tarsal claws arranged in one S­shaped row, and Homostola Simon, 1892 , where the male characters are unknown) – by an elevated eye tubercle, by the absence of both the metatarsal preening combs and a well­developed rastellum, and by the biserially toothed tarsal claws in males;

(d) from the Nemesiidae (North­African species of Nemesia Audouin, 1826 , Iberesia Decae & Cardoso 2006 , and Amblyocarenum Simon, 1892 ) – by a shorter straight thoracic fovea, by a much longer and slender male palpal tibia, by the absence of cheliceral rastellar teeth, and from members of the first two genera – by an unmodified male tibia I lacking megaspines;

(e) from Pionothele Purcell, 1902 (the only African genus of Pycnothelidae known hitherto), which species share with members of Afromygale n. gen. a reduced unpaired tarsal claws – in having an anteriorly narrowed sternum, acuspulate maxillae and thickened legs III–IV vs. subcircular sternum, armed maxillae and equally slen­ der legs I–IV in males of Pionothele spp. ( Figs 2, 6, 14 cf. Figs 24, 34; Zonstein 2016, figs 1, 4, 9, 12; Bond & Lamb 2019, figs 2, 3).

Additionally, males of Afromygale n. gen. differ from all other male pycnothelids in having a very characteristic pterygoid (or a fin­shaped) keel located at the base of the embolus. The similar structures, one or several, if present in males in other pycnothelid genera are differently constructed ( Figs 9, 10, 17, 18 cf. Forster 1968, figs 451–453; Main 1972, figs 10, 14, 18, 20; Goloboff 1995, figs 66A–C, 67E, 74C–E, 80E–G, 95E, 96D, Passanha et al. 2014, figs 4–6, 9–11, 13, 24–26, 29–31, 34–36, 39–41, 44–46, 48–50, 53–55; Pérez­Miles et al. 2014, fig. 4A; Indicatti et al. 2017, figs 7–9, 12–14, 17–19, 21, 22, 41–46, 49–51, 56–58.

Description: Medium­sized mygalomorphs (body length 14.8–16.8 mm). Carapace low, oval and densely hirsute, with cephalic part almost indistinctly elevated over thoracic portion. Clypeus narrow. Thoracic fovea short, deep and straight. Eye tubercle, carrying all eight eyes, well defined and highly elevated. Chelicerae without mound and rastellar spines or teeth; dorsodistal cheliceral edge with dense brush of thickened hairs and spikes. Fang without serration. Labium moderately long and narrow, nearly subquadrate, without cuspules. Sternum narrowed anteriorly. Labiosternal sigilla fused. Anterior and medium sternal sigilla small submarginal. Posterior sternal sigilla minute, oval and located remotely from sternal margin. Maxillae trapezoidal, acuspulate at least in males. Male palpal tibia long, slender and subcylindrical, without spines. Cymbium short, subglobular and aspinose. Embolus tapered with one pronounced keel at its base. Leg formula 4123, legs III and IV insufficiently thicker than legs I and II. Male tibia I unmodified, without megaspines. Metatarsal preening combs absent. Metatarsi I–IV ventrally either entirely ascopulate or with a few scopuliform hairs near distal edge. Male tarsi I–IV flexible and pallid ventrally ( A. pinnipalpis n. sp.) or rather entire and rigid ( A. rukanga n. sp.). Short, fine, entire and relatively dense ventral scopula well developed on tarsi I–III but absent on tarsus IV. Trichobothria arranged in two convex rows on tibiae, one straight row on metatarsi and one relatively narrow zigzag row on tarsi. Tarsal organ low and domed. Paired claws on tarsi I–IV broad and biserially dentate with numerous teeth. Unpaired tarsal claw always present, though reduced in size (more in A. pinnipalpis n. sp., less in A. rukanga n. sp.), and very sharply curved downwards. Two pairs of spinnerets: PMS medium­sized, PLS relatively thick and short with apical segment certainly shortened. All spigots uniform and visually appear belonging to the same type (MAS not evident, only AC type present). State of maxillary serrula, male intercheliceral glands and female characters unknown.

Species included: A. pinnipalpis n. sp. and A. rukanga n. sp., both currently known only from males.

Distribution: Southern Kenya and northeastern Tanzania ( Fig. 1).