Titiotus, SIMON, 1897

Platnick, Norman I. & Ubick, Darrell, 2008, A Revision of the Endemic Californian Spider Genus Titiotus Simon (Araneae, Tengellidae), American Museum Novitates 3608 (1), pp. 1-36 : 2-4

TITIOTUS SIMON

Titiotus Simon, 1897: 113 (type species by original designation Titiotus californicus Simon ).

DIAGNOSIS: The unusual character combination of three claws plus claw tufts readily separates members of Titiotus and their closest relatives from most other North American spiders. Males of Titiotus differ from those of the other three closely related genera ( Liocranoides Keyserling , Anachemmis Chamberlin , and Socalchemmis Platnick and Ubick ) by having a tibial apophysis consisting of three or four prongs (rather than just one or two, figs. 9, 14); females differ by having a wide median septum that usually occupies more than two-thirds of the epigynal width (figs. 10, 15).

DESCRIPTION: Medium to large spiders, total length of males 8–17, of females 11–21. Carapace oval, widest at rear of coxae II, abruptly narrowed at level of palpi to less than two-thirds of maximum width; thoracic groove long, longitudinal, very deep; surface coated with short recumbent and fewer, longer, erect dark setae, erect setae most numerous along midline and in ocular area; eight eyes in two rows; from above, both eye rows slightly recurved; from front, anterior row recurved, posterior row slightly procurved; anterior median eyes round, smallest; other eyes oval, subequal, with canoe-shaped tapeta; anterior median eyes separated by roughly their diameter, slightly closer to anterior laterals; posterior medians separated by roughly their diameter, much farther from posterior laterals; lateral eyes of each side separated by almost their diameter; median ocular quadrangle wider in back than in front, wider in back than long; clypeal height about twice diameter of anterior median eyes, corners of clypeus with incised margins that overlie cheliceral boss; chilum weakly sclerotized, divided, composed of two triangular sclerites. Chelicerae vertical, anterior surface with few, erect setae; promargin with three teeth situated at proximal end of fang furrow, most proximal tooth smallest, middle tooth largest, retromargin with three larger, more distally situated teeth; very short, narrow, Ishaped posterior sclerite present, separating chelicerae at base. Labium short, only about half as long as endites, distally invaginated at middle, reflexed at almost 90 ° angle relative to sternum. Endites rectangular, distally slightly convergent, with anteromedian scopula and anterolateral serrula consisting of single row of teeth. Sternum rounded, without extensions to coxae, with only slight angular projections between coxae, with erect setae; posterior margin only slightly extended between coxae IV.

Leg formula 4123. Typical leg-spination pattern (only surfaces bearing spines listed): femora: I d1-1-1, p0-2-1, r1-1-1; II d1-1-1, p2- 2-1, r0-1-2; III d1-1-1, p2-1-1, r1-2-1; IV d1-1- 1, p1-1-1, r0-0-2; patellae III, IV p0-1-0, r0-1- 0; tibiae: I, II p1-1-0, v4-6-4; III d1-0-1, p0-1-1, v2-2-2, r1-1-1; IV d1-0-1, p0-1-1, v2-2-2, r1-0- 1; metatarsi: I v2-2-2; II p1-0-0, v2-2-2, r1-0-0; III p1-1-2, v2-2-1r, r1-1-2; IV p1-1-2, v2-2-1r, r1-2-2; tarsi with three claws and claw tufts, superior claws with several weak teeth, most distal teeth largest, inferior claws unarmed; all tarsi with strong ventral scopulae, scopular hairs distinct from those of claw tufts; distal segments apparently with trichobothria in two rows; tarsal organ not scanned; all trochanters strongly notched; males without tibial crack; metatarsi without preening combs.

Abdomen without anterior or dorsal scutum; anterior lateral spinnerets large, composed of two articles, distal article with two major ampullate gland spigots and about 25 piriform gland spigots (figs. 1, 4); posterior median spinnerets composed of one article, small, triangular, those of female expanded posteriorly, where they bear single large and two smaller cylindrical gland spigots, preceded anteriorly by several smaller aciniform gland spigots and terminally by two minor ampullate gland spigots (figs. 2, 5); posterior lateral spinnerets composed of two articles, distal article about one-fourth as long as proximal article, with numerous long aciniform gland spigots and (in female) three larger cylindrical gland spigots (figs. 3, 6); colulus represented by setae on small lobe.

Male palp with patella not widened, tibial apophysis complex, consisting of three or four prongs, of which two or three most retrolateral often share common base (fig. 9); subtegulum and tegulum with interlocking lobes, median apophysis heavily sclerotized at least distally, bearing multiple processes; embolus short, arched, accompanied by hyaline conductor (figs. 7, 8). Female palp with extremely long, dentate claw. Epigynum with wide median septum, usually occupying most of epigynal width (fig. 10); spermathecal bulbs situated posterolaterally.

SPECIES GROUPS: Two groups are recognized; the californicus group, containing most of the species, is characterized by having the most ventral prong of the tibial apophysis relatively long and narrow, and situated close to the base of the cymbium. Members of the humboldt group, containing only the new species T. humboldt , T. marin , and T. costa , have the most ventral prong of the tibial apophysis relatively short and wide, and situated close to base of the retrolateral prongs.