Birabenella homonota, Grismado, 2010

Grismado, Cristian J., 2010, Description of Birabenella, a New Genus of Goblin Spiders from Argentina and Chile (Araneae: Oonopidae), American Museum Novitates 2010 (3693), pp. 1-24 : 7-11

Birabenella homonota , new species

Figures 1 , 3–9 , 15–35 , 69

TYPE MATERIAL: Male holotype from Chile: Coquimbo Region: Elqui Province: Cuesta Porotitos ; 29°47′ 40.1″S; 71°17′ 31.8″W ( WGS84 ); alt. 106 m ( GPS); 16.VIII.2009; coll. C. Grismado, A. Ojanguren, J. Pizarro and F. Alfaro. Coastal shrubby steppe, under stones. Deposited in MHNS ( PBI _ OON 14989). Same data: two female paratypes (MACN-Ar 22098, 22097, PBI _OON 14991, 14990 respectively) .

OTHER MATERIAL EXAMINED: None.

ETYMOLOGY: The specific epithet refers to the gekkonid genus Homonota Gray , very common lizards at the site where these spiders were collected. The reticulate carapace of these oonopids resembles the scaly skin of these lizards.

DIAGNOSIS: B. homonota is the only known species with ventral spines on tibiae and metatarsi I–II (figs. 3–4). Males resemble those of B. argentina in general palpal conformation, but differ in the dorsally bulging bulb, the shape of the apical membranous elements that accompany the embolus and the obtuse ventral protrusion on the palpal tibia (figs. 31–33). Females differ from other species in having a highly coiled tube of the posterior receptaculum (fig. 35) and a strongly reticulate surface of the carapace and sternum.

DESCRIPTION: Male (holotype): Total length 1.74. CEPHALOTHORAX: Carapace orange; surface of elevated portion of pars cephalica strongly reticulate, sides strongly reticulate, nonmarginal pars cephalica setae dark, needlelike, scattered; nonmarginal pars thoracica setae dark; marginal setae dark. Clypeus setae dark, needlelike. Sternum orange, with radial furrows between coxae I–II, II–III, III–IV, surface finely reticulate, microsculpture covering entire surface, lateral margins with rounded extensions between coxae. Mouthparts: setae dark. Chelicerae, endites, and labium orange; labium with 1 or 2 setae on anterior margin, subdistal portion with one medial setae. Endites converging anteriorly, tip with one strong, spinelike projection.

ABDOMEN: Dorsal scutum weakly sclerotized, pale orange, narrow, with irregular margins, reaching to around the middle of the dorsum, without color pattern, covering less than 1 ⁄ 2 of abdomen, between 1 ⁄ 4 and 1 ⁄ 2 abdomen width, not fused to epigastric scutum, surface smooth. Setae: dorsal stout and flattened; epigastric and postepigastric needlelike, all dark. LEGS: pale orange; patella plus tibia I nearly as long as carapace. Leg spination (only surfaces bearing spines listed, all spines longer than segment width): leg I: femur: p0-0-1, pv0-0-1; tibia: v2-2- 2-0; metatarsus: v2-2, leg II: tibia: v2-2-2-0; metatarsus: v2-2. Tarsi I to IV superior claws unipectinate. Trichobothria not examined. GENITALIA: Palpal bulb with rounded dorsal bulge, distally with distinct, small, digitiform ventral apophysis, embolus accompanied by a large retrolateral membranous element, both arising from broad opening of bulb; tibia with ventral obtuse median projection.

Female (paratype, MACN-Ar 22098, PBI_OON 14991): Total length 2.04. As male except where noted. CEPHALOTHORAX: Carapace slightly broader anteriorly compared with the male. Clypeus high, ALE separated from edge of carapace by their radius or more. Eyes all subequal; ALE-PLE separated by ALE radius to ALE diameter. Mouthparts: Endites convergent anteriorly, anterior tip without the spinelike projection of males. Female palp spines absent.

ABDOMEN: dorsum soft portions white. Dorsal scutum less than 1 ⁄ 4 abdomen width, narrow, with irregular margins, shorter than that of male. LEGS: cuticular sculpture reticulate, at least on tibiae and metatarsi (figs. 3–4), fingerprint in tarsi (figs. 5–6). Leg spination (only surfaces bearing spines listed, all spines longer than segment width): leg I: femur: p0-0-1, pv0-0-1; tibia: v2-2-2-0; metatarsus: v2-2, leg II: tibia: v2-2-2-0; metatarsus: v2-2. Trichobothria (only metatarsal and tibial examined with SEM): base longitudinally narrowed, internal texture of the aperture not gratelike, hood covered by low, closely spaced ridges, hood and distal plates not well differentiated. Tarsal organ with 3 sensilla visible, capsulate, opening intermediate between oval and longitudinal slit. GENITALIA (figs. 34–35): anterior process and its transverse widened structure relatively small; posterior receptaculum with anterior wall strongly sclerotized, apparently dorsally folded, with long, irregularly convoluted internal duct.

NATURAL HISTORY: The three known specimens were collected under stones in Cuesta Porotitos (fig. 1), in a typical habitat of the shrubland steppe subregion of central Chile. The plant formations of the type locality correspond to the “coastal shrubby steppe,” as described in Gajardo (1993).

Figures

FIGURE 69. North-central Chile and northwestern Argentina, showing the geographic distribution of Birabenella species: B. argentina (squares); B. homonota and B. elqui (triangle) and B. pizarroi (circle).

FIGURES 1–2. Habitats of Birabenella species in Coquimbo, Chile. 1, Cuesta Porotitos, the type locality of B. homonota, n. sp., and B. elqui, n. sp. 2, disturbed grassland Near Quebrada del Quereo, Los Vilos, type locality of B. pizarroi, n. sp.

FIGURES 3–6. Birabenella homonota, n. sp., female paratype (PBI_OON 14990), morphology of left leg I. 3, tibia, prolateral; 4, metatarsus, prolateral; 5, tarsus, prolateral; 6, tarsal claws, prolateral.

FIGURES 7–9. Birabenella homonota, n. sp., female paratype (PBI_OON 14990), left leg I. 7, claws and claw tufts, apical; 8, same, detail (arrow: tarsal organ); 9, tibial trichobothria, dorsal.

FIGURES 15–22. Birabenella homonota, n. sp., male holotype (PBI_OON 14989). 15–17, 22, habitus; 18–19, 21, cephalothorax; 20, abdomen. 15, 18, dorsal; 16, 19–20, ventral; 22, anterior; 17, 21, lateral. Arrow: dorsal scutum.

FIGURES 23–30. Birabenella homonota, n. sp., female paratype (PBI_OON 14991). 23–25, 30, habitus; 26–27, 29, cephalothorax; 28, abdomen. 23, 26, dorsal; 24, 27–28, ventral; 30, anterior; 25, 29, lateral. Arrow: dorsal scutum.

FIGURES 31–35. Birabenella homonota, n. sp., genital morphology. 31–33, male holotype (PBI_OON 14989), left palp. 31, 33, prolateral; 32, retrolateral (E = embolus; arrow: ventral digitiform projection of the bulb). 34–35, female paratypes (PBI_OON 14991 and 14990, respectively); 34, epigastric area, ventral; 35, internal genitalia, cleared, dorsal view (PR = posterior receptaculum).