Prionosternum Dunn

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 : 219-221

Prionosternum Dunn

Prionosternum Dunn, 1951: 13 (type species by original designation Prionosternum scutatum Dunn ).

DIAGNOSIS: Males can be recognized by their porrect chelicerae and small, simple retrolateral tibial apophysis (figs. 534, 538), females by their epigynal conformation, with paired anterior epigynal hoods and bipartite spermathecae (figs. 536, 537).

DESCRIPTION: Medium size spiders, total length of males 3.5–4.2, of females 4.0–4.4. Carapace reddish brown, pars thoracica coat­ ed with anastomosing rows of large tubercles, pars cephalica with long, dark, thin setae but fewer tubercles; thoracic groove long, longitudinal, deep. Eight eyes in two rows, anterior medians smallest, circular, dark, laterals subequal in size, oval, light, posterior medians largest, irregularly oval, flattened, light; from above, both eye rows slightly procurved, from front, both rows procurved; anterior medians separated by more than their radius, closer to anterior laterals; posterior medians separated by less than their radius, much farther from posterior laterals; anterior and posterior laterals separated by almost their diameter; median ocular quadrangle wider in back than in front, longer than wide in front. Chelicerae, sternum, and mouthparts reddish brown; chilum wide, short, triangular, accompanied by second, longitudinal posterior chilum (extremely narrow sclerite separating bases of chelicerae posteriorly); chelicerae with distinct lateral boss, anterior surface with depressed, relatively unsclerotized oval area near promargin; promargin with two rows of long setae originating in line along base of fang, seta closest to fang not bent near base, not extending behind oth­ er promarginal setae to near midline; promargin with three teeth, median one largest, proximal one smallest; retromargin with two large, narrowly separated teeth; male chelicerae porrect, with deep median excavation, borders of excavation with strong tubercles. Labium elongate, triangular, only gradually narrowed anteriorly, posterior margin truncate, anterior margin very slightly invaginat­ ed at middle, surface slightly depressed medially. Endites obliquely depressed, with sharply demarcated, deep groove along margin near labium, groove wider anteriorly than posteriorly; serrula long, with single row of teeth; anterior surface with distinct sieve plate of maxillary gland openings set in oval of unsclerotized cuticle. Sternum slightly elevated, with gently sloping lateral margins, not expanded anteriorly, with triangular extensions to and between coxae; surface with few punctations. One epimeric sclerite on each side, above each coxa, not reaching sternal triangles, not fused to carapace or pedicel. Pedicel consisting of large, diamond­shaped sclerite bearing wide anterior margin meeting posterior tip of sternum at slightly procurved line.

Anterior edge of abdomen of male with complete sclerotic ring formed by strong epigastric scutum plus strong dorsal abdominal scutum covering entire front edge of abdomen, reaching to more than three­fourths of abdominal length, females with dorsal scutum represented only by small transverse plate above pedicel, restricted to lower half of anterior surface of abdomen; cuticle with long, 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 pair of long setae; posterior spiracle procurved, inconspicuous. Anterior lateral spinnerets tubular, separated at base by about 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, conical, of females with anteriorly expanded tips, bases occupied by three enormously widened cylindrical gland spigots; posterior lateral spinnerets two­segmented, those of females with at least one greatly widened cylindrical gland spigot.

Leg spination reduced; typical leg spination pattern (only surfaces with spines list­ ed): femur IV d1­0­0; tibiae: III v1p­0­2; IV v1p­1p­2, r0­0­1; metatarsus IV v1p­1p­0. Most leg surfaces with long setae; both sexes with all coxae dorsally tuberculate; anterior coxae with slightly protuberant posterolateral corners, widened at about half their length; trochanters unnotched; anterior tarsi with weak, divided scopulae, composed of laterally directed setae; posterior metatarsi with thick, distal preening brushes; posterior tarsi with weak scopulae; tarsi with two dentate claws, claw tufts composed of lateral pads of short, closely appressed setae, restricted to ventral portion of claw tip; trichobothria present on distal leg segments, in two rows. Female palpal tibia and tarsus with long, thin spines; female palpal tarsus with long, basally dentate claw.

Male palp with short retrolateral tibial apophysis; cymbial surface not excavated opposite tibial apophysis; tegulum bulbous, with slight median projection; embolus short, originating at middle of prolateral side of bulb, extending behind hooked median apophysis, accompanied behind median apophysis by short, angular conductor; embolar base without apophysis. Epigynum with paired anterior hoods; spermathecae bipartite, accompanied by anteromedian ducts.

KEY TO SPECIES OF PRIONOSTERNUM

1. Males.............................. 2

– Females (those of P. porongorup unknown) ................................. 4

2. Palpal tibia with distinct dorsal apophysis at about one­third its length (fig. 535)............................... scutatum

– Palpal tibia with only small dorsal expansion (figs. 471, 539).................... 3

3. Retrolateral tibial apophysis relatively short, stubby (figs. 538, 539)....... nitidiceps

– Retrolateral tibial apophysis longer, on distinct base (figs. 470, 471)....... porongurup

4. Anterior epigynal hoods relatively long (fig. 536)....................... scutatum

– Anterior epigynal hoods relatively short (fig. 540)...................... nitidiceps