Penestomus Simon 1902
Creators: name: Miller, Jeremy A.
name: Griswold, Charles E.
name: Haddad, Charles R.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Penestomidae
Penestomus

description: Genus Penestomus Simon, 1902
Penestomus Simon, 1902: 241. Type species by monotypy Penestomus planus Simon, 1902. Simon, 1903: 980;
Lehtinen, 1967: 257, 385-390; Dippenaar-Schoeman, 1989: 131.
Wajane Lehtinen, 1967: 275. Type species by monotypy Wajane armata Lehtinen, 1967. Dippenaar-Schoeman, 1989: 133. New synonymy.
Justification of synonymy. Wajane was described by Lehtinen (1967) based on a single male specimen. At the time, Penestomus was known only from females. The chief diagnostic character for distinguishing Penestomus from Wajane was the lack of a cribellum in the latter. However, male spiders almost never have a cribellum, even when conspecific females do, and Lehtinen himself speculated that Wajane females could have a functional cribellum (Lehtinen 1967: 387). Dippenaar-Schoeman (1989) described W. stilleri in the genus Wajane based on its reported lack of a cribellum but electron microscopy of W. stilleri non-type material clearly indicates that a functional cribellum is present (Fig. 8 F). A total of three penestomid species are now known from males. While all differ in detail (especially of the pedipalp), there are no obvious characters that would suggest two distinct clades that could be circumscribed as Penestomus and Wajane. Wajane is thus hereby synonymised with Penestomus.
Diagnosis. Distinguished from other three-clawed, eight-eyed, cribellate entelegyne spiders except Eresidae by their subrectangular carapace (Fig. 1 B) and clypeal hood (Fig. 1 C); distinguished from Eresidae by the flat body (Fig. 1 A), tapetum in the indirect eyes (Fig. 1 D), RTA on the male pedipalpal tibia and by the position of the posterior lateral eyes, which are several eye diameters behind the posterior median eyes in Eresidae but are less than three eye diameters behind the posterior median eyes in Penestomidae (Fig. 1 C). Distinguished from the ecribellate Zodariidae by the presence of a cribellum (Fig. 5 A) and calamistrum (Fig. 4 C), a serrula on the endites (Fig. 2 A), a clypeal hood (Fig. 1 C), and by the absence of tarsal trichobothria.
Description. Flat spiders (Fig. 1 A). Total length 3-6. Carapace subrectangular with shallow ovoid fovea. Eight eyes in two rows, posterior eye row slightly recurved, more widely spaced than anteriors (Fig. 1 C). Tapetum present in indirect eyes (ALE, PLE, PME), at least that of PME appears to be canoe-shaped (Fig. 1 D). Carapace, legs, and abdomen usually with two setal morphologies, one black and filiform, the other white and plumose (Figs 1 B, E). Sternum ovoid, longer than wide, not fused to labium (Fig. 1 F). Endites parallel, with serrula. Anterior surface of labrum with bifid lingual process (Fig. 2 B). Chelicerae with boss (Fig. 2 C). Promargin of fang furrow armed with four-six teeth increasing in size from base of fang to the penultimate tooth; proximal tooth small. Retromargin of fang furrow armed with two-three teeth (Fig. 2 D; contra Dippenaar-Schoeman 1989; Lehtinen 1967). Respiratory system with pair of book lungs anteriorly; posterior tracheal system (examined in a penultimate juvenile of P. egazini sp. nov.) quadritracheate, with four simple, subequal tubes restricted to abdomen. Female pedipalp with dentate claw; tarsus with pro-ventral cluster of macrosetae. Leg tarsi each with multidentate paired claws and untoothed median claw (Fig. 2 E); scopula absent. Tarsal organ capsulate, on slightly raised base; opening circular (Fig. 2 F). Tibiae each with two dorsal rows of trichobothria; metatarsi each with one dorsal trichobothrium distally; bothria hooded (Fig. 4 A); tarsi without trichobothria. Male tibiae and metatarsi I with clusters of retrolateral macrosetae (Figs 3B-D); tibiae II-IV with visible transverse suture near base (Fig. 3 A; see also Griswold 1993, 1994; Griswold et al. 2005). Female with calamistrum, a single row of setae occupying distal two thirds of metatarsus IV (Fig. 4 C). Female cribellum divided with two fields of strobilate spigots (Figs 5 E, F). Female anterior lateral spinnerets (ALS) with two major ampullate gland spigots (MAP) on squat bases, these invaginated into piriform (PI) field, four PI on tall tapered bases, plus approximately four tartipores (Fig. 5 B). Female posterior median spinnerets (PMS) with two minor ampullate gland spigots (mAP), one aciniform gland spigot (AC), one tartipore, and two cylindrical gland spigots (CY; Fig. 5 C). Female PLS with one modified spigot (MS) flanked by two nubbins, four aciniform gland spigots (AC), one tartipore, and one CY (Fig. 5 D). Paracribellar spigots absent from both the PLS and PMS. Male cribellum vestigial, lacking spigots (Fig. 6 A). Male ALS with one MAP on a squat base plus one nubbin, these within the PI field, four PI on tall tapered bases, and approximately three tartipores. Male PMS with one mAP, one nubbin (representing a mAP), one anterior AC, and one tartipore (Fig. 6 C). Male PLS with one nubbin (representing the MS), seven AC, and three tartipores (Fig. 6 D). Epiandrum with two clusters of about 5-10 spigots (Fig. 4 B).
FIGURE 1. Penestomus egazini sp. nov. females from Grahamstown, South Africa (A, C, E, F, CASENT 9024961; B, CASENT 9023774; D, CASENT 9024964). A, prosoma, lateral view; B, live female with egg case under Eucalyptus bark; C, prosoma, anterior view, arrow indicates clypeal hood; D, light micrograph showing tapetum in posterior median eyes; E, detail of carapace, lateral view, showing plumose and filiform types of setae; F, prosoma, ventral view. A, C, E- F, scanning electron micrographs; B, field photograph; D, light micrograph of specimen under stereomicroscope. Scale bars A, F = 100 µm; C, E = 30 µm; D = 0.1 mm.
Male pedipalpal tibia with apophyses arising from the retrolateral part of tibia (the retrolateral tibial apophysis or RTA), which comprise an inner ramus of the RTA (RTA 2) that arises apically near the base of the cymbium (Fig. 7 B) and an outer, bifid ramus of the RTA (RTA 1) that arises basally on the tibia and that is divided apically into inner RTA1(I) and outer RTA1(O) tips (Fig. 7 F). Base of RTA1 with ridge (R). Median apophysis (MA) anchored to retrolateral side of tegulum by membranous tissue, with notched plate on retrolateral side and long tailpiece extending transversely across the proximal tegulum to prolateral side of bulb (Fig. 7 C). Conductor (C) retroapical, fleshy, translucent (Figs 7 D, 10 A). Embolus makes a half turn, tip expanded and complex, rests against conductor in unexpanded conformation (Figs 7 C, 10 A). Expansion of the bulb reveals a long, narrow, heavily sclerotized petiole that extends two-thirds the retrolateral height of the alveolus, the prodorsal surface of the tegulum with a conical projection that fits into a corresponding depression on the subtegulum (Fig. 11 B), and a reservoir that makes a simple loop around the margin of the tegulum and subtegulum, without switchbacks.
FIGURE 2. Penestomus egazini sp. nov. from Grahamstown, South Africa (A, B, E, F, female, CASENT 9024964; C, D, male, CASENT 9024985), scanning electron micrographs. A, detail of endite showing serrula, anterior view; B, labrum, anterior view, chelicerae removed, arrow indicated bifid lingual process; C, chelicera, lateral view, arrow indicates boss; D, chelicera showing fang and teeth; E, claws, left tarsus IV; F, tarsal organ, tarsus I. A, B taken from specimen with chelicerae removed; C shows chelicera removed from prosoma and mounted separately. Scale bars A, E, F = 20 µm; B = 30 µm; C, D = 100 µm.
Female genitalia entelegyne, epigynum divided into anterior lobe (AL) and posterior lobe (PL; Fig. 12 A). Epigynum usually mushroom-shaped (a subtriangular anterior lobe with a long, narrow posterior lobe), occasionally subpentagonal (Fig. 16 E). Median projection of AL runs posteriorly into PL, divided from PL by a groove laterally and posteriorly (Fig. 8 A). Pair of (usually membranous) posterolateral apophyses (PA) arise from AL on either side of the median projection (MP)/PL complex (Figs 8 A, E). AL usually with pair of unsclerotized anterolateral patches (Fig. 12 A). Spermathecae (S) usually subspherical, occasionally ovoid (Figs 8 B, 16 H); fertilization ducts (FD) and copulatory ducts (CD) originate from posteromesal region of spermathecae (Fig. 12 D). CD path direct, gently curved or sinuous, running posteriorly from spermathecae (Fig. 8 B). FD relatively robust, gently curved, running posteriorly from spermathecae (Fig. 8 B).
Previous authors have erroneously suggested that penestomids lack teeth on the posterior margin of the fang furrow (Dippenaar-Schoeman 1989; Lehtinen 1967). The lack of posterior margin teeth has also been claimed in eresines, although in fact the teeth are merely small (Griswold et al. 2005: fig. 131 D). Lehtinen (1967: 388) asserted that there were instead two rows of teeth along the anterior margin. In fact, penestomids have four to six teeth on the promargin and two to three teeth on the retromargin of the fang furrow (Fig. 2 D).
Species groups. Based on morphology of female genitalia, most penestomid species resemble the type species P. planus in possessing a mushroom-shaped epigynum (a subtriangular anterior lobe with a long, narrow posterior lobe; Fig. 16 A). Penestomus croeseri and P. stilleri are both quite distinct from the P. planus configuration and from each other. All remaining species (P. planus, P. egazini sp. nov., P. kruger sp. nov., P montanus sp. nov., P. prendinii sp. nov., P. zulu. sp. nov.) are placed in the planus group. Females of planus group species are distinguished from P. stilleri by the subspherical spermathecae (Figs 8 B, 12 B, D, F, 16 D; ovoid in P stilleri, Fig. 16 H); from P croeseri by the connection between the AL and its MP (as wide as the MP in planus group species, Figs 12 A, C, E, 16 A, B, C; distinctly narrower in P. croeseri, Fig. 16 E). Since the female of P. armatus is unknown, it is not possible to infer its affinities at this time. But if the female is discovered and it resembles P. croeseri, P. stilleri, or has a unique configuration, this could justify the resurrection of Wajane.
Additional specimens examined
The following are unidentified juvenile specimens from unique localities (gray circles, Fig. 21). These may represent additional Penestomus species or range extensions of some of the species treated here. Researchers are encouraged to search for adults from these locations.
SOUTH AFRICA: Eastern Cape: 1 juvenile, Dunbrody, Uitenhage District [33°45'S, 25°23'E], 1902, J.A. O'Neil (SAM-ENW-XO12418, SAM); Gauteng. 1 juvenile, Magaliesburg, Jackal's Kloof [26°0'S, 27°30'E], 28 March 1999, J. Leeming (AcAT 2000/253, JDL 00106, NCA); KwaZulu Natal: 1 juvenile, Umgeni Valley, nr Howick [29°30'S, 30°15'E], 2 March 1992, J. Leroy (AcAT 94/628, LR 875, NCA); 1 juvenile, Sani Pass [29.621°S, 29.3895°E], September 2007, pitfall traps, grassland, D. Prentice (AcAT 2008/588, NCA); Limpopo: 10 juveniles, Lajuma, Western Soutpansberg [23°S, 30°E], 31 August 1997, in leaf base of palm tree, S. Foord (AcAT 2001/296, NCA); Western Cape: 4 juveniles, Karoo National Park [32°17'S, 22°26'E], 1 April 1994, on top of mountain, on radio mast, A. Leroy (AcAT 95/318, NCA); 1 juvenile, Karoo National Park, near Beaufort West [32°17'S, 22°26'E], 3 April 1989, web in grass, A. Leroy (AcAT 89/708, LR 369, CAS); 1 juvenile, same data, 6 October 1989, under rock (AcAT 91/358, LR 537, NCA); 1 juvenile, same data, 5 October 1989, under flat rock, B. Schumann (AcAT 91/363, LR 570, NCA); 1 juvenile, Karoo National Park, Puttersvlei [32°17'S, 22°26'E], 3 April 1989, A. Leroy (AcAT 96/246, LR 1184, NCA); 1 juvenile, Mossel Bay [34°10'S, 22°7'E], 14 April 1899, J.L. Drege (SAM-ENW-X005370, 5390, SAM); 1 juvenile, Saldanha Bay, Jutten Island [33°0'S, 17°56'E], June 2005, B. Dyer (SAM-ENW-C005354, NL570, SAM); 1 juvenile, same data (SAM-ENW-C005355, NL571, SAM); 1 juvenile, same data, (SAM-ENW-C 005356, NL572, SAM).
description: Published as part of Miller, Jeremy A., Griswold, Charles E. & Haddad, Charles R., 2010, Taxonomic revision of the spider family Penestomidae (Araneae, Entelegynae), pp. 1-36 in Zootaxa 2534 on pages 6-34