Morebilus, PLATNICK, 2002

PLATNICK, NORMAN I., 2002, A Revision Of The Australasian Ground Spiders Of The Families Ammoxenidae, Cithaeronidae, Gallieniellidae, And Trochanteriidae (Araneae: Gnaphosoidea), Bulletin of the American Museum of Natural History 2002 (271), pp. 1-1 : 1-

Morebilus , new genus

TYPE SPECIES: Hemicloea plagusia (Walckenaer) .

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

DIAGNOSIS: As these animals are among the largest Australian gnaphosoids, it isn’t surprising that they include the earliest described trochanteriids. Although many of these taxa have previously been misplaced in the gnaphosid genus Hemicloea , they closely resemble Rebilus in spinneret and tarsal claw morphology, but can be distinguished from members of that genus by the inclined lip at the anterior edge of the sternum (fig. 505), which is accompanied laterally by a pair of greatly enlarged intercoxal sclerites (fig. 351).

DESCRIPTION: Large spiders, total length of males 10–16, of females 10–24. Carapace flattened (fig. 353), without tubercles, with rebordered lateral margins, evenly coated with scattered, dark, stiff, erect setae interspersed among white, recumbent setae; few longer, erect, dark setae present (pair at rear of pars cephalica, one opposite each coxa, one at each anterolateral corner and pair crossing at midline of clypeus); thoracic groove long, Y­shaped, wider anteriorly than posteriorly; cephalic groove pronounced, accompanied by three additional intercoxal grooves on each side. Eight eyes in two rows (fig. 354), anterior medians largest, circular, dark, posterior medians smallest, circular, lenses slightly flattened but canoe­shaped tapetum apparently still present, laterals subequal, almost as large as anterior medians, oval; from above, anterior eye row slightly procurved, posterior row slightly recurved, from front, both eye rows almost straight; anterior medians separated by more than their diameter, by more than twice their diameter from anterior laterals; posterior medians separated by more than six times their diameter, about as far from posterior laterals; anterior and posterior laterals separated by more than their diameter; median ocular quadrangle much wider in back than in front or than long. Chelicerae porrect, divergent, with distinct oblique groove just below clypeus (fig. 352); anterior surface with stiff setae along inner margins; chilum very wide, triangular, unipartite but with small area of unsclerotized cuticle along ventral one­third of midline area, accompanied by second, elongated, posterior chilum (narrow, I­shaped sclerite separating bases of chelicerae posteriorly); chelicerae with distinct lateral boss, promargin with series of long setae originating in line along base of fang, those nearest base of fang unmodified; promargin with three teeth, proximal tooth smaller than others, distalmost tooth widely separated from other two, retromargin with two widely separated teeth; presumptive cheliceral gland openings on distinct mound, surrounded by concentric ridges, situated proximal to basal retromarginal tooth. Labium rectangular, flat, posterior one­quarter narrowed, anterior margin truncate. Endites long, divergent, with oblique depression restricted to their median edge; serrula absent (fig. 155), long, oval, sieve plate conspicuous under light microscopy; anteromedian edges and apex bearing wide patch of long, stiff, dark setae. Sternum flat, with rebordered, slightly depressed lateral margins, expanded anteriorly into inclined lip, with only indistinct extensions to coxae, extensions between coxae represented by three pairs of small triangular sclerites separated from sternal margin by unsclerotized cuticle, additional, much larger pair of triangular sclerites situated opposite lateral edges of sternal lip; surface smooth, with few long setae, posterior margin not rebordered, separating coxae IV. One weakly sclerotized epimeric sclerite on each side, not extending between coxae, not fused to carapace. Pedicel composed of two dorsal sclerites (anterior sclerite with deep posterior invagination receiving beak­shaped anterior extension of posterior sclerite) and weak, inverted v­shaped ventral sclerite with anteriorly expanded head not reaching posterior tip of sternum.

Abdomen without dorsal or anterior scutum; cuticle with weak, recumbent setae; epigastric scutum weakly sclerotized, with well­ marked booklung openings at sides but without postepigastric sclerites, booklung covers strongly ridged; colulus represented only by scattered setae situated near narrow posterior spiracle; male with long epiandrous spigots in two clusters on each side (figs. 346, 347). Anterior lateral spinnerets short, conical, separated by about their diameter at base, with two articles, distal article with two major ampullate gland spigots and numerous small, unmodified piriform gland spigots (number larger in females than in males; figs. 339, 340); posterior median spinnerets without aciniform gland spigots, those of males triangular, with only two minor ampullate gland spigots (fig. 341), those of females bipartite, anterior portion with same two minor ampullate gland spigots (fig. 342), enlarged posterior portion with two parallel rows, each row with about 12–14 large cylindrical gland spigots (fig. 344); posterior lateral spinnerets with two articles, without minor ampullate gland spigots, those of males with aciniform gland spigots only (fig. 343), those of females with two large cylindrical gland spigots in addition, tartipores of aciniform gland spigots elongate (fig. 345).

Legs laterigrade, subequal in length, most surfaces with long setae; coxae and trochanters without dorsal tubercles, fourth trochanters slightly elongated; anterior coxae without protuberant posterolateral corners; trochanters very slightly notched, producing sharp point at ventralmost edge; anterior metatarsi and tarsi with undivided scopula composed of short, straight setae; posterior metatarsi with distal preening brushes composed of row of long, thick setae; tarsi with two long, smooth claws bearing no ventral teeth, strong claw tufts composed of two large pads of narrow setae; tarsi without cuticular cracks, extremely short; morphologically dorsal surface with modified proximal margin consisting of patch of unsclerotized cuticle followed by strong cuticular ridge, that ridge opposing distinct distal extensions situated at distal edge of metatarsi; trichobothria present, in three rows on tarsi, two on metatarsi and tibiae, bases with pair of overlapping ridges (fig. 348). Female palpal femur with strong dorsal spines, distal segments with weaker but longer spines; female palpal tarsus with long claw bearing three to five tiny ventral teeth, without ventral scopula. Typical leg spination pattern (counts refer to morphological surfaces, only surfaces bearing spines listed): femora I–IV d1­0­0; tibiae: I v3­2­2; II v4­2­2; III, IV v1p­1p­0; metatarsi: I v2­1p­0; II v2­3­0; III v1p­0­0.

Male palpal tibia with pair of basal retrolateral protuberances, retrolateral apophysis usually present, sometimes represented mainly by thick spines; cymbium with thick distal scopula; cymbial surface distinctly invaginated opposite retrolateral tibial apophysis; tegulum elongated, with medially situated, long, basally wide embolus extending across middle of bipartite median apophysis, accompanied by distally membranous conductor. External epigynum large, usually with large, excavated atrium.

Species Groups: Two informal species groups can be recognized. The plagusius group includes M. plagusius (Walckenaer) , M. swarbrecki (Dunn and Dunn) , and the new species M. graytown , M. gramps , M. fitton , and M. gammon ; in these species, the anterior portion of the internal female genitalia consists of a pair of small, thumbshaped projections. The remaining species constitute the diversus group, in which the anterior portion of the internal female genitalia consists of a pair of large, kidneyshaped or globose bulbs.