Boagrius Simon, 1893

Zonstein, Sergei L. & Marusik, Yuri M., 2020, A review of the spider genus Boagrius Simon, 1893 (Araneae: Palpimanidae), Raffles Bulletin of Zoology 68, pp. 91-102 : 92-93

Boagrius Simon, 1893

Boagrius Simon, 1893a: 405 ; Deeleman-Reinhold, 2001: 52, figs. 76, 77; Jocqué & Dippenaar-Schoeman, 2006: 196, fig. 75b, c.

Type species. Boagrius pumilus Simon, 1893 , by monotypy.

Diagnosis. By possessing a similar state of some characters (a bipartite thoracic fovea, relatively long and slender legs I–IV, a weakly swollen femur I, and a poorly developed leg scopula), the considered genus resembles members of Levymanus Zonstein & Marusik, 2013 , distributed in the eastern part of Africa and in the Near East ( Figs. 1B, 1J , 2 A–H cf. Zonstein & Marusik, 2013: figs. 1, 2, 10, 11, 26–31). All other chedimine genera, except for those discussed here, embrace species possessing a pit-like or a slit-like thoracic fovea, a stouter femur I, and a better developed leg scopula (see Zonstein & Marusik, 2013: figs. 1–9; 2017a: figs. 3–8, 11–15, 19, 40–42; 2017b: fig. 1A–E; Zonstein et al., 2016: figs. 1–6; 2018: figs. 1–4; Marusik & Zonstein, 2018: figs. 1–5, 12, 13).

Boagrius can be clearly distinguished from Levymanus by: a) having a more compact cephalothorax with shorter and narrowed anterior and posterior parts; b) the presence of an elevated hump in the median part of the carapace; c) the relatively smaller AMEs (which are two to three times as large as other eyes); d) a shorter distance between the thoracic sulci; and e) a shorter abdomen with a considerably shorter petiolar tube ( Figs. 1A, B , 2 A–H, 3A–C, 3E–L). In species of Levymanus , the carapace is longer and narrower anteriorly and posteriorly, the thoracic hump is not as conspicuous, the AMEs four to five times as large as other eyes, the distance between the thoracic sulci is noticeably broader, and the abdomen is longer with an unusually long petiolar tube (cf. Zonstein & Marusik, 2013: figs. 10–15, 33–34; Zonstein et al., 2017: fig. 1A–F).

Description. Small bicolour chedimine palpimanids with body length 2.1–2.4 mm in males and 2.6–2.8 mm in females. Carapace domed and oval, slightly narrowed and truncated anteriorly and posteriorly, densely and finely corrugated ( Fig. 1A ), with elevated hump between eye group and thoracic fovea. Eight eyes. AME largest, about two to three times larger than other eyes, which are subaequal in size. ALE and PLE almost touching each other. PME widely spaced from each other, as well as from AMEs and from PLEs. Clypeus about two times higher than AME diameter. Chilum inconspicuous. Thoracic fovea short and bipartite, with two separate sulci closely located side by side ( Fig. 1B ). Posterior notch deep subtriangular ( Fig. 1C ). Chelicerae relatively small, only slightly longer than clypeus; stridulatory ridges absent; cheliceral fang serrate; cheliceral furrow without true or peg teeth ( Fig. 1 D–F). Sternum shield-like, widest between coxae I and II, with fine reticulation; labium about as broad at base as it is long. Maxillae short and moderately wide ( Fig. 1G, H ).

Palps moderately short, with thickened distal segments in females ( Fig. 1I ); legs I–IV long and slender. Leg formula: 1423. Leg cuticula fairly smooth. Femur I rather long and weakly swollen; patella I thin and long (longer than tibia). Tibia and metatarsus I with weakly developed prolateral scopula ( Fig. 1J ). Leg tarsi straight (not curved), with two narrow unidentate claws and ascopulate ( Fig. 1K, L ). Claw tufts weakly developed.

Abdomen ovoidal, slightly extended anteriorly and obtuse posteriorly, without dorsal pattern (uniformly pale coloured) in unsclerotised part. Abdominal scuta conforming a rather short pedicel tube; dorsal portion of scutum relatively small. Small spinneret group set on low mound. AMS small, cylindrical, two-segmented; PMS and PLS reduced to a few sessile spigots in females and absent in males.

Male palp ( Figs. 3C, D , 4 A–I, 5A–L). Femur longer than wide (ca. 2.3), equal in length to tibia and cymbium; patella more than two times shorter than femur; tibia strongly swollen, ca 1.6 thicker than femur; cymbium and bulb not embedded into the tibia; cymbium with sparse ‘scopular’ setae; bulb longer than cymbium, with two outgrowths, the tegular apophysis (Ta) and embolus (Em); tegular apophysis long (subequal to the length of tegulum), straight, with bent and bifurcated tip; embolus well sclerotised, relatively long (equal or ca. 1.5 times shorter than tegular apophysis), partly screwed (bent around the axis), with thin apophysis (Ea).

Female copulatory organ ( Fig. 6 A–F). Posterior edge of epigastric scutum bow-like, shallowly concave in median part, posterior edge of epigastric furrow (postgastric area) with two or three thin scuta, two lateral and one median (not distinct in B. pumilis ), all these scuta almost invisible maceration. Endogynes differ in two species, wider than long (ca. 3 times in the type species and ca. 1.5 in the new species); each receptacle (Rl + Rt) with three grape-like glands (Gg); receptacles in type species with pore gland field (Pg) anteriorly.

Composition. Boagrius currently includes two named species: B. pumilus Simon, 1893 , and B. simoni , new species.

Distribution. South-East Asia: Singapore and Malaysia (mainland part and Borneo).

Figures

Fig. 1. Scaled SEM micrographs of somatic structures of Boagrius pumilus (subadult female from Bukit Fraser, Malaysia). A, carapace, anterior view; B, thoracic fovea, dorsal; C, posterior notch of carapace; D–F, chelicera, anteroventral, ventral, and posteroventral view, respectively; G, H, palpal endites, ventral; I, palp, prolateral; J, leg I, tibia to tarsus, prolateral; K, apex of tarsus I, showing tarsal claws and tufts, anterior view; L, same, leg IV, retrolateral view.

Fig. 2. A–D, habitus of Boagrius pumilus; E–H, habitus of B. simoni, new species; A, B, E, F, males; C, D, G, H, females; A, C, E, G, dorsal view; B, D, F, H, lateral view. Scale bar = 1 mm.

Fig. 3. A–F, cephalothorax of Boagrius pumilus; G–I, cephalothorax of B. simoni, new species; A–D, G–I, males; E, F, J, K, females; A, E, G, J, dorsal view; B, F, H, K, ventral view; C, D, I, anterior part of cephalothorax in dorsal, ventral, and anterior view, respectively. Scale bar = 0.25 mm.

Fig. 4. A–D, details of male palp of Boagrius pumilus; E–I, details of male palp of B. simoni, new species; A, E, entire palp, retrolateral; B, F, same, prolateral; C, D, G, distal part of palp, ventral; H, I, same, proventral. Scale bar = 0.25 mm.

Fig. 6. A, B, female copulatory organs of Boagrius pumilus; C–F, female copulatory organs of B. simoni, new species; A, endogyne, receptacles, and accessory structures, ventral view; B, D, same, posterior view; C, E, F, same, dorsal view.Scale bar = 0.25 mm. Abbreviations: At, atrium; Ft, fine thread; Gg, grape-shaped gland; Pg, pore gland; Rl, Rt, longitudinal and transversal parts of receptacle, respectively.