Dysderina Simon

Platnick, Norman I. & Berniker, Lily, 2013, The South American goblin spider genera Dysderina and Tridysderina (Araneae, Oonopidae), American Museum Novitates 2013 (3772), pp. 1-52 : 3-21

Dysderina Simon

Dysderina Simon, 1891: 556 (type species by original designation Oonops principalis Keyserling ).

DIAGNOSIS: Specimens belonging to this genus can be distinguished from all other members of the Dysderina complex by their distinctive sternal morphology: each side of the sternum bears three deep, steeply sided excavations extending from the sides of the sternum toward the midline (figs. 11, 41, 146, 176).

DESCRIPTION: Total length of males 1.6–2.3, of females 1.8–2.9. Carapace, sternum, mouthparts, abdominal scuta, legs orange-brown, without pattern; abdomen soft portions white, without pattern. Cephalothorax: Carapace broadly oval in dorsal view, anteriorly narrowed to 0.49 times its maximum width or less, pars cephalica strongly elevated in lateral view, anterolateral corners with strongly sclerotized, triangular extension, pars thoracica with rounded posterolateral corners, without depressions or radiating rows of pits, posterolateral edge without pits, posterior margin not bulging below posterior rim, posterolateral surface without spikes; surface of elevated portion of pars cephalica smooth (fig. 1), reticulate (fig. 136), or with some low granules (figs. 31, 166), sides granulate (figs. 2, 32, 167), granules sometimes low (fig. 137); fovea absent, lateral margin straight, rebordered, with blunt denticles (except in D. tiputini , which has nearly smooth lateral margins with few, low denticles, fig. 167); plumose setae near posterior margin of pars thoracica absent; marginal, nonmarginal pars cephalica, pars thoracica setae light, needlelike, scattered. Clypeus margin strongly rebordered, sinuous in front view (figs. 3, 33, 138, 168), vertical in lateral view, high, ALE separated from edge of carapace by their radius or more, median projection present, formed by fused small, triangular chilum; setae light, needlelike. Eyes six, well developed, ALE largest, oval, PME squared, PLE oval; posterior eye row recurved from above, procurved from front; ALE separated by more or less than their radius, ALE-PLE separated by less than ALE radius, PME touching throughout most of their length, PLE-PME separated by less than PME radius. Sternum wider than long, not fused to carapace, surface smooth, without pits, median concavity, hair tufts absent, radial furrows between coxae I–II, II–III, III–IV enlarged into deep, smooth, steeply sided excavations (figs. 11, 41, 146, 176), posterior edges of excavations sometimes connected by transverse ridges (figs. 11, 41, 103, 114); radial furrow opposite coxae III absent, other microsculpture absent, sickle-shaped structures absent, anterior margin with continuous transverse groove, posterior margin not extending posteriorly of coxae IV but with posterior hump, anterior corner excavated, lateral margins with infracoxal grooves bearing anterior, posterior openings, distance between coxae approximately equal, extensions of precoxal triangles absent, lateral margins with bridges to coxae; setae sparse, dark, needlelike, densest laterally, originating from surface, posterior and lateral margins with conspicuous, tuberculate setal bases. Chelicerae slightly divergent, anterior face with swelling; with one large tooth on promargin, without teeth on retromargin (figs. 4, 5, 34, 35, 139, 140, 169, 170); fangs without toothlike projections, directed medially, shape normal, without prominent basal process, tip unmodified; setae dark, needlelike, densest medially; paturon inner margin with scattered setae, distal region, posterior surface unmodified, promargin with row of flattened setae, inner margin unmodified, laminate groove absent, inner margin slightly excavated in males of D. sasaima , more deeply excavated in males of D. baehrae and D. excavata , with thick brush of setae in males of D. excavata . Labium triangular, not fused to sternum, anterior margin not indented at middle, same as sternum in sclerotization; with six or more setae on anterior margin, most lateral seta on each side usually enlarged (figs. 36, 171), subdistal portion with unmodified setae. Endites same as sternum in sclerotization, serrula apparently absent (figs. 7, 37, 142, 172), anterior portion modified in males (figs. 6, 141), distally excavated in males of D. principalis and D. urucu , posteromedian part unmodified, females often with heavily rebordered anteromedian margins. Female palp without claw or spines (figs. 38, 39, 173, 174); tibia with three trichobothria (figs. 40, 175), patella without prolateral row of ridges, tarsus elongate. Abdomen: Ovoid, without long posterior extension, rounded posteriorly, interscutal membrane without rows of small sclerotized platelets. Booklung covers large, ovoid, without setae, anterolateral edge unmodified; both posterior and anterior spiracles usually connected by grooves, but anterior groove represented only by medially extended slits in some females, apparently absent in females of D. excavata and D. ayo ; posterior groove continued beyond spiracles almost to lateral edge of postepigastric scutum (figs. 66, 93). Pedicel tube medium, ribbed, scutopedicel region unmodified, scutum extending far dorsal of pedicel, plumose hairs, matted setae on anterior ventral abdomen in pedicel area, cuticular outgrowths near pedicel all absent. Dorsal scutum strongly sclerotized, covering full length of abdomen, no soft tissue visible from above, not fused to epigastric scutum, middle surface smooth, sides smooth, anterior half without projecting denticles. Epigastric scutum strongly sclerotized, surrounding pedicel, not protruding, small lateral sclerites absent, without lateral joints in females. Postepigastric scutum strongly sclerotized, anterior margin unmodified, with short posteriorly directed lateral apodemes, in males covering nearly full length of abdomen, semicircular or almost rectangular, fused to epigastric scutum, in females almost as long, not fused to epigastric scutum. Spinneret scutum reduced or absent in males (fig. 235), present as incomplete ring with fringe of long setae in females (fig. 82); supraanal scutum absent. Abdominal setae light, needlelike, epigastric area setae not basally thickened; dense patch of setae anterior to spinnerets absent, interscutal membrane with setae. Colulus present, tiny, with pair of setae. Anterior lateral spinnerets bisegmented, basal segment without oblique membranous strip (figs. 12, 42, 147, 177), posterior medians unisegmented, posterior laterals bisegmented; spigots scanned only in three species, anterior laterals of males with one major ampullate gland spigot and four piriform gland spigots (figs. 13, 148), of females with one major ampullate gland spigots and 6–13 piriform gland spigots (figs. 43, 178), posterior medians of males with two or three minor ampullate gland spigots with convex bases and two or three aciniform gland spigots with excavated bases (figs. 14, 149), of females with three minor ampullate gland spigots with convex bases and 6–13 aciniform gland spigots with excavated bases (figs. 44, 179), posterior laterals of males with five or six minor ampullate gland spigots with convex bases and two aciniform gland spigots with excavated bases (figs. 15, 150), of females with six minor ampullate gland spigots with convex bases and 6–17 aciniform gland spigots with excavated bases (figs. 45, 180). Legs: Femur IV not thickened, same size as femora I–III, patella plus tibia I shorter than carapace, tibia I unmodified, tibia IV specialized hairs on ventral apex, ventral scopula absent, metatarsi I, II mesoapical comb absent, metatarsi III, IV weak ventral scopula absent. Leg spines present on anterior femora, tibiae, metatarsi; femoral spines strong, tibial, metatarsal spines long, spines absent on posterior legs. Tarsi without inferior claw. Superior claws, scanned only in three species, usually with four, five, or six stout teeth on outer row, five or six longer teeth on inner row (figs. 17–24, 48–55, 183–190), but outer row of teeth missing in at least males of D. tiputini (figs. 152–159). Trichobothrial base with rectangular aperture (figs. 25, 160). Tarsal organs with three receptors on legs I, II, two on legs III, IV, palps (figs. 26–30, 56–60, 161–165, 191–195). Genitalia: Male epigastric region with sperm pore small, situated between anterior and posterior spiracles, rebordered (figs. 16, 151); furrow without Ω-shaped insertions, without specialized setae. Male palp of normal size, not strongly sclerotized, right and left palps symmetrical, proximal segments, cymbium yellow; embolus dark, prolateral excavation absent; trochanter of normal size, unmodified; femur dorsoventrally enlarged (figs. 9, 144), two or more times as long as trochanter (figs. 8, 143), without posteriorly rounded lateral dilation, attaching to patella basally; patella shorter than femur, not enlarged, without prolateral row of ridges, setae unmodified; tibia with three trichobothria (figs. 10, 145); cymbium ovoid in dorsal view, completely fused with bulb, no seam visible, extending beyond distal tip of bulb, plumose setae, stout setae, distal patch of setae all absent; bulb shorter than cymbium, slender to stout, elongated. Sclerotized embolus (distal prong) and sclerotized conductor (proximal prong) originating from same base but separate for most of their length (figs. 68, 214). Female genitalia externally with small but distinct atrium bearing rebordered anterior and posterior margins (figs. 46, 181), internally with anterior genitalic process (figs. 47, 182), process typically widened at base, apodemes short.

DISTRIBUTION: Known only from Colombia, Ecuador, and Brazilian Amazonia; none of the many taxa that have been assigned to the genus in the past are actually congeneric with the type species .

SPECIES GROUPS: Two informal species groups are recognized. The principalis group includes those species in which the posterior edges of each of the three pairs of sternal excavations on each side of the sternum are connected by strong, transverse ridges (figs. 11, 64). The tiputini group includes those species in which the sternum has no transverse ridges (figs. 146, 196).