Bigenditia, PLATNICK, 2000

PLATNICK, NORMAN I., 2000, A Relimitation And Revision Of The Australasian Ground Spider Family Lamponidae (Araneae: Gnaphosoidea), Bulletin of the American Museum of Natural History 2000 (245), pp. 1-328 : 215-216

Bigenditia , new genus

TYPE SPECIES: Bigenditia zuytdorp , new species.

ETYMOLOGY: The generic name is an arbitrary combination of letters, considered feminine in gender.

DIAGNOSIS: Males can easily be recognized by the highly modified chelicerae, which have a projection on each side of the base of the fang, and endites, which have greatly expanded anterolateral corners; females are easily recognized by their massive, deeply excavated and rebordered epigyna with longitudinal median ridges (figs. 528, 533). These are the only known Australian centrothelines in which the sternum has fused with the ventral part of the pedicel (that character occurs also in the New Caledonian genus Centrocalia ).

DESCRIPTION: Medium to large spiders, total length of males 6.1–6.5, of females 6.9– 7.3. Carapace dark red, surface coated with large tubercles, sparsely set with long, dark setae; thoracic groove long, longitudinal, deep. Eight eyes in two rows, anterior medians circular, dark, larger than subequal, oval, light laterals, posterior medians largest, irregularly oval, flattened, light; from above, both eye rows almost straight, from front, both rows strongly procurved; anterior me­ dians separated by more than their radius, closer to anterior laterals; posterior medians separated by much less than their radius, much farther from posterior laterals; anterior and posterior laterals separated by more than their diameter; median ocular quadrangle wider in back than in front, wider in back than long. Chelicerae, sternum, and mouthparts dark orangish red; chilum wide, triangular, tuberculate, accompanied by second, Ishaped, posterior chilum (extremely narrow sclerite separating bases of chelicerae posteriorly); chelicerae tuberculate except on distinct lateral boss, sparsely set with long, dark setae, anterior surface with depressed, relatively unsclerotized oval area near promargin; promargin with row of long setae originating in line along base of fang, seta closest to fang bent near base at almost 908 angle, extending behind other promarginal setae to near midline; promargin with three teeth, median one largest, proximal one smallest; retromargin with two large, widely separated teeth; cheliceral gland openings presumably in excavated, reticulate area medial of proximal retromarginal tooth. Chelicerae of males highly modified, with large, dark projections both anterior and posterior of fang base. Labium elongate, base narrowed at about onethird of labial length, posterior margin procurved, anterior margin medially invaginat­ ed, surface depressed medially. Endites obliquely depressed, with sharply demarcat­ ed, wide, deep groove along margin near labium, groove wider anteriorly than posteriorly; serrula long, strong with single row of teeth. Endites of males highly modified, with large, dark projections at anterolateral corners. Sternum slightly elevated, with slightly sloping lateral margins, not expanded anteriorly, with triangular extensions to and between coxae; surface tuberculate, with distinct elevations opposite, and depressions between, coxae. One epimeric sclerite on each side, above each coxa, entirely fused to sternal extensions, including extensions between coxae I and endites, and between coxae IV, fused area constituting base of pedicel, reaching around sides of pedicel, but not fused above pedicel, not fused to carapace. Dorsal elements of pedicel not fused with sternum.

Anterior edge of abdomen of male with complete sclerotic ring formed by strong epigastric scutum; additional strong dorsal scutum reaches to about two­thirds of abdominal length, females with dorsal scutum reduced to small strip above pedicel, not fused to epigastric scutum; cuticle with short, recumbent setae; epigastric scutum accompanied posterolaterally by pair of oval, deeply invaginated sclerites bearing clearly elevated anterior rim; sclerites separated by membranous lobe, anterior rim of sclerites fitting under epigastric scutum; colulus represented only by setae; tiny transverse sclerite, well removed from spinnerets, marking position of small posterior spiracle. Anterior lateral spinnerets tubular, separated by more than their diameter, cuticle representing distal, second spinneret segment restricted to semicircle surrounding major ampullate gland spigots (piriform gland spigots surrounded only by soft cuticle); posterior median spinnerets of males large, tubular, of females with anteriorly expanded tips, bases occupied by three enormously widened cylindrical gland spigots; posterior lateral spinnerets two­segment­ ed, those of females with two greatly widened cylindrical gland spigots.

Leg spination reduced only on anterior legs; typical leg spination pattern (only surfaces with spines listed): tibiae III, IV v1p­ 2­2; metatarsi III, IV p0­0­1, v2­2­2, r0­0­1. Most leg surfaces with short setae originating from large, tuberculate bases; anterior coxae with slightly protuberant posterolateral corners; trochanter very slightly notched; anterior metatarsi and tarsi with divided scopulae, composed of laterally directed setae; posterior metatarsi with thick, dark, distal preening brushes; tarsi III, IV with sparse, divided scopulae; tarsi with two dentate claws, claw tufts composed of lateral pads of closely appressed setae. Female palpal tibia, and tarsus with long, thin spines; female palpal tarsus with long, basally dentate claw.

Male palp with strong retrolateral tibial apophysis; cymbial surface excavated opposite tibial apophysis, not produced into distinct lobe on ventral side of tibial apophysis; tegulum largely restricted to retrolateral side of bulb, bearing large, laterally expanded median apophysis opposing large, elongated terminal apophysis; embolus originating posteriorly, long, occupying prolateral side of bulb, accompanied distally by long, heavily sclerotized conductor; embolar base without apophysis. Epigynum with anterior hood fused to elevated median, longitudinal ridge; atrium on either side of ridge deep, frequently filled with hard plug; spermathecae extended anteriorly beyond epigynal hood.

KEY TO SPECIES OF BIGENDITIA

1. Median apophysis relatively wide (fig. 526); posterior margin of epigynum transverse (fig. 528)................... zuytdorp

– Median apophysis relatively narrow (fig. 530); posterior margin of epigynum oblique (fig. 532)........................ millawa