Melchisedec, Fannes, 2010

Fannes, Wouter, 2010, On Melchisedec, a new genus of the spider family Oonopidae (Araneae, Dysderoidea), American Museum Novitates 2010 (3702), pp. 1-28 : 6-12

Melchisedec , new genus

TYPE SPECIES: Melchisedec thevenot , new species. ETYMOLOGY: The generic name is a patronym honoring the French author and inventor Melchisédec Thévenot (ca. 1620–1692), an important patron of the new, experiment-oriented science of his day. Gender masculine.

DIAGNOSIS: Melchisedec can be distinguished from all other oonopid genera by the following combination of features: dorsal and ventral scuta well developed, covering most of abdomen (figs. 2, 26, 27); epigastric furrow situated in middle of abdomen (fig. 26); ventral pedicel sclerite with a crestlike outgrowth that bears a row of transverse ridges (figs. 57, 60, 61); metatarsi I and II with scepterlike setae on both sides of lyriform organ (figs. 42, 43).

DESCRIPTION: Small- to medium-sized (TL 1.17–1.48, CL 0.53–0.61) oonopid spiders with well-developed abdominal scuta. CEPHALOTHORAX: Carapace yellow or orange, without any pattern, longer than wide, anteriorly narrowed to approximately 0.5 times its maximum width (fig. 3), pars cephalica elevated ( M. thevenot ; fig. 55) or flat ( M. birni ; fig. 56) in lateral view; anterolateral corners without extensions or projections, posterolateral corners rounded, posterolateral edge without pits, posterior margin not bulging below posterior rim, posterolateral surface without spikes; pars thoracica without depressions or radiating rows of pits; lateral margin straight, rebordered; dorsal surface smooth (fig. 3), each lateral surface completely covered by microsculpture (figs. 6, 55, 56) except for two small, smooth regions located immediately dorsal of the lateral margin; these regions are slightly elevated above the surrounding cuticle (fig. 7). Clypeus high, ALE separated from edge of carapace by more than their diameter (figs. 4, 5), clypeus margin curved downward in front view, without median projection; usually eight needle-shaped setae on clypeus, arranged in typical pattern: four anteromedially projecting setae near margin; two upward-projecting setae situated centrally on clypeus; two medially projecting setae situated anterior of ALE (fig. 5). On dorsal surface of carapace a U-shaped row of approximately 16 setae and a central row of about four setae. Eyes six, well developed, ALE oval, wider than long, PME oval, longer than wide, PLE oval, longer than wide, posterior eye row recurved from above; ALE separated by less than their diameter, ALE-PLE separated by less than ALE radius, PME-PME touching or almost touching, PLE-PME separated by less than PME radius (figs. 3–5); just outside each ALE a medially projecting seta, no setae between ALE, between each PME and PLE a medially projecting seta (fig. 5). Sternum approximately as long as wide, uniformly yellow or orange, fused to carapace; median concavity absent, sickleshaped structures absent, without pits, without posterior hump, posterior margin not extending posteriorly of coxae IV, anterior corners unmodified. A median band of reticulated microsculpture extends along length of sternum. Radial furrows between coxae I–II, II–III, III–IV; furrows covered with reticulated microsculpture (fig. 8). Abundant setae on sternum; posteriormost setae arranged in two longitudinal rows of 2–3 setae each (fig. 10). Coxal insertions I, II, and III each with two clusters of small openings (fig. 7); coxal insertion IV without clusters. In male M. thevenot a pouch behind the labium (fig. 9). A curved, dark-red ridge between each coxal insertion IV and the pedicel (fig. 10). Anterior face of paturon pale grey or orange, unmodified, bearing relatively few setae. Labium same as sternum in sclerotization. Endites converging but tips not touching, anteromedian tip and posteromedian part unmodified, same as sternum in sclerotization. Female palp without spines; patella without row of ridges; tibia longer than patella, on dorsal surface three trichobothria (fig. 18), prolateral surface presenting two pairs of robust setae (fig. 19); tarsus longer than tibia, not expanded (fig. 20). Pedicel with one dorsal and one ventral sclerite. Dorsal sclerite flat, posteriorly drawn out into a point (fig. 57), not fused to prosoma. Ventral sclerite U-shaped, covering ventral and lateral sides of pedicel; anteriorly fused to prosoma; ventral surface forming a crestlike elevation; crest bearing a row of transverse ridges (figs. 57, 60, 61; see Pedicel morphology, below, for more details). ABDOMEN: ovoid in dorsal view, without long posterior extension (fig. 2), interscutal membrane with setae, without rows of small sclerotized platelets. Book lung covers medium sized, elliptical, darker than surrounding scutum, without setae, anterolateral edge without tubercle. Anterior spiracles not discernible with a stereomicroscope. Posterior spiracles connected by groove (figs. 26, 27, 29). Each posterior spiracle with a fine furrow that runs toward lateral margin of PES (fig. 31). Epigastric furrow situated in middle of abdomen (fig. 26). Pedicel tube short, without dorsolateral triangular extensions or fringe of setae (fig. 23). Scutopedicel region without scutal ridges (figs. 21, 22); matted setae on anterior ventral abdomen in pedicel area absent. DS strongly sclerotized, without color pattern, covering all or most of dorsum, not fused to ES, anterior half without projecting denticles. Relatively few setae on DS, needle shaped. Surface of DS smooth except for sides of anterior half, which are finely reticulate in many individuals. ES strongly sclerotized, surrounding pedicel, not extending far dorsal of pedicel, small lateral sclerites absent. In females posterior margin of ES procurved at middle (figs. 26, 28, 29). PES strongly sclerotized. In females PES considerably shorter than ES, leaving approximately 1/4 of abdomen length uncovered (fig. 26). PES fused to ES in male M. thevenot (fig. 27). Spinneret scutum present, incomplete ring with a fringe of about 13 needlelike setae. Anal scutum present, lightly sclerotized. Supraanal scutum absent. LEGS: without spines, patella plus tibia I shorter than carapace; coxae white, other segments yellow; tibia I unmodified; femur IV not thickened, same size as femora I–III. Legs covered with long, needlelike setae (fig. 37). Tarsi and metatarsi with shorter, densely barbed setae interspersed between the needlelike setae (fig. 37); these setae curved in lateral view (fig. 38), their sockets rounder than those of needlelike setae (fig. 37). On the anterior and posterior surface of each coxa a group of 2–3 smooth setae (fig. 39); smooth setae variable in length (fig. 39), consisting of smooth shaft and asymmetrical socket (figs. 40, 41), projecting into the narrow space between adjacent legs. Metatarsi I–II with scepterlike setae on both sides of lyriform organ (figs. 42, 43); scepterlike setae very short, with truncated apex, smooth except for distal ring of fine cuticular extensions (fig. 43); scepterlike setae occurring either as a single, isolated seta or as a closely spaced pair (figs. 42, 43). Metatarsi III–IV usually without scepterlike setae. Each leg with four dorsal trichobothria: one on proximal tibia, two on distal tibia, one on distal metatarsus (fig. 35).

GENITALIA: Females lacking external copulatory structures (figs. 29, 30). Male M. thevenot with a long, inward-curved ECC (figs. 46, 48–50).

DISTRIBUTION: Known from Guinea-Bissau, Ivory Coast, Nigeria, Niger, Cameroon, and Ethiopia (fig. 1).

NOTE: Melchisedec is found from Guinea-Bissau to Ethiopia (fig. 1). Its distribution thus spans the entire width of the African continent. In spite of this vast geographic range, specimens of Melchisedec are exceedingly rare in museum collections. The oonopid collection of the Royal Museum for Central Africa (Tervuren, Belgium), which totals more than 7800 adult spiders, was found to contain only 17 specimens of Melchisedec (0.2% of the total). No specimens were found in the collections of the British Museum, the Uppsala University Museum, or the Zoological Museum of the University of Copenhagen.