Monodontium bukittimah, Raven, 2008

Raven, Robert J., 2008, A Revision Of The Mygalomorph Spider Genus Monodontium Kulczynski (Barychelidae: Araneae), Raffles Bulletin of Zoology 56 (1), pp. 29-44 : 37-41

Monodontium bukittimah , new species

( Figs. 1 , 5A–H , 6A–F ; Tables 3, 4)

Material examined. – Holotype. Male , Bukit Timah Hill, Singapore, [1º20'N 103º47'E], J. Wunderlich, 1986 ( ZRC –ARA–459).

Allotype female. Bukit Timah Nature Reserve , Jungle Fall Valley, 100 m (rainforest along small stream), 9 Jun.2001, P. Schwendinger, SIM01/01 ( MNHG).

Diagnosis. – Differs from other species in the presence of rastellar spines and in the rectanguloid eye group and from M. mutabile in that PME are larger (relative to PLE) and the centres of the eyes of the back row form a recurved line whereas in M. mutabile the line is clearly procurved.

Etymology. – A noun in apposition from the type locality.

Description. – Holotype, male (ZRC–ARA–459): Carapace 2.16 long, 1.68 wide. Abdomen 1.65 long, 1.27 wide. Total length, 4.0.

Colour in alcohol: Carapace dark orange-brown, chelicerae dark red-brown, and legs yellow-brown, not annulated. Abdomen dorsally dark brown; ventrally pallid.

Carapace: Pilosity: lightly setose but without hairs; striae indistinct, shallow, narrow. Bristles: 1–2 long erect black beside posterior striae; ca. 5 anteromedially and 8–10 in band beside caput; 4–6 long thick and no finer between PME, and 1 long thick recurved and 3–5 finer between ALE; ca. 10 long bristles on each lateral margins. Fovea broad, straight.

Eyes: Tubercle distinct. Three rows. Back row straight. Eye group occupies 0.40 of head-width; front width, back width, length, 26:30:15. MOQ front width, back width, length, 15:21:10. AME:ALE:PME:PLE, 7:9:4:6. Eye interspaces: AME–AME, 0.3, AME–ALE, 0.3, ALE–ALE, 2.1, PME– PME, 2.7, ALE–PLE, 0.6.

Chelicerae: With narrow band of bristles prodorsally, laterally a narrow band of setae. Rastellum is 4 long strong spines, 2 on raised bases but not on common mound, on inner distal corner overhanging fang. Intercheliceral tumescence evidently absent. Furrow promargin with 2 small distal and 2 small basal and one tooth at mid-length, basomesally with no teeth evident.

Labium: 0.36 wide, 0.20 long; lightly setose with 4–5 setae transversely behind midpoint. Labiosternal suture a narrow shallow groove. Cuspules absent.

Maxillae: 0.69 long in front, 0.87 long behind, 0.34 wide; without cuspules or incipient spines. Heel distinctly produced, squared; anterior lobe broad and indistinct.

THE RAFFLES BULLETIN OF ZOOLOGY 2008

Sternum: 1.06 long, 0.87 wide. Sigilla not evident.

Legs: Tibia I with slightly raised spur distoventrally with triangular apex, above that a stout curved megaspine, microspur absent. Femur III incrassate but much less so than in M. sarawak , new species. Mid-width 1.14 times basal and 1.06 wider than distally.

Scopula: Entirely absent.

Spines: Leg 1: fe d3w; pa 0; ti p1v3 + megaspines; me p2v1. Leg 2: fe d3; pa 0; ti v4; me p2v0. Leg 3: fe p3d3r1; pa p2v1; ti p2d3r1v6; me p3r3v6. Leg 4: fe p1d5w; pa r1; ti p3d2r3v12; me p3r3v8. Palp: fe d2w; rest, 0.

Claws: Three to five teeth in each of two rows (I–II), one row entally on III, on leg IV bare.

Trichobothria: In two rows, each of 8 for length of tibiae; ca. 8 on metatarsi in slightly diagonal row; ca. 10 small filiform on tarsi, none clavate.

Palp: Bulb relatively large quickly tapering to short flanged embolus; cymbium bilobed, dorsal lobe broadly pointed, prolateral lobe almost semi-circular; no tuft distally on cymbium. Cymbium short, with group of long strong spinelike setae basally on dorsum.

Spinnerets: PMS absent. PLS 0.20 apart, 0.11 wide basally; length of basal, middle, apical, and total articles 0.23, 0.11, 0.06, 0.40, respectively.

Description. – Allotype, female (MNHG): Carapace 2.12 long, 1.60 wide. Abdomen 2.32 long, 1.52 wide. Total length, 6.0.

Colour in alcohol: Carapace brown with darker marks on lateral caput forming narrow median pallid zone to fovea, darker markers also along lateral margins and interstrial ridges, chelicerae light brown, maxillae, labium, and sternum fawn, legs fawn with indistinct darker areas on lateral femora and tibiae. Abdomen dorsally brown; ventrally pallid.

Carapace: Pilosity: glabrous; striae distinct, wide; bases of 5 thick anteromedial bristles from eyes to fovea; two lines, each of about 10, posteriorly-directed bristles extend from PME to fovea (i.e., foveal bristles) along lateral borders of medial pallid zone; 2 thick and 6 smaller bristles between PME; 3 long and 4 shorter between AME; 1 long bristle in posterior striae; few fine bristles on lateral margins. Fovea straight. Clypeus absent.

Eyes: Tubercle distinct. In two rows; front strongly procurved so anterior edge of AME and posterior edge of ALE in line, back row slightly recurved. Eye group occupies 0.33 of headwidth; front width, back width, length, 26, 30 and 17, respectively. MOQ front width, back width, length, 14, 21, 11, respectively. AME:ALE:PME:PLE, 5: 7: 5: 6. Eye interspaces: AME–AME, 0.4; AME–ALE, 1.0; ALE–PLE, 0.8; PME–PME, 2.6; ALE–ALE, 1.6.

Chelicerae: With narrow band of spaces thin brown bristles prodorsally, laterally with few fine hairs. Rastellum of 2–3 long thick curved spines on inner edge and about 10 thinner but strong spines in transverse line laterally; three long spines above group on inner edge. Furrow promargin with 6 teeth, basomesally with group of about 10 long fine teeth.

Labium: 0.22 long, 0.44 wide. One short blunt cuspule beside a short pointed spine; labiosternal suture narrow.

Maxillae: 0.58 long in front, 0.74 long behind, 0.50 wide; with 8–9 cuspules in inner angle. Heel large, broad, rounded; anterior lobe indistinct. Anterior face with pallid groove for length just above lower edge, groove dorsally bordered by narrow band of two lines of short setae. No lyra evident on chelicerae entally or ectally.

Sternum: 1.00 long and wide. Only small, oval, marginal posterior sigilla evident.

Legs: Coxae I, II with slightly pronounced heel.

Scopula: For length of metatarsi I but thin, divided widely; absent on II–IV. Tarsi: palp and I, thin, sparse, widely divided by band 6–8 setae wide; absent on II–IV.

Palp: Claw tufts absent; “cage” of thicker setae around base of claw on tarsus edge, 4 in long vertical line laterally and group of about 5 below claw with two thicker spine-like setae just basal.

Spines: Only long curved bristles on femora and patellae, and on tibiae I, II; none on leg tarsi. Leg 1: me v1.1.1–3. Leg

THE RAFFLES BULLETIN OF ZOOLOGY 2008

2: me v1.1.1.3. Leg 3: pa p2 thorns; ti p1r1v2w; me p1.2r1.1.1v1.2.3. Leg 4: pa p0; ti r1v1.2.3w; me p2r2v1.1.1.3. Palp: fe 0; pa 0; ti v3w; tarsus v 3w.

Claws: Three to four teeth on paired claws of legs I–II in two rows; three teeth on prolateral faces on IV, none on other face; three short teeth on inner face of palpal claw. Claw tufts on I–IV distinct, wide, reach at least to curve of claws.

Trichobothria: As for M. malkini .

Spermathecae: A broad based lobe apically with two hornlike tips.

Spinnerets: PMS absent. Basal, middle, apical, total segments of PLS, 0.31, 0.20, 0.08, 0.74 long, respectively.

Distribution and Habitat. – Known only from tropical rainforest on Bukit Timah Hill, Singapore.

Remarks. – Cuspules are often lost entirely or represented only by incipient spines in males (noted by Raven, 1994) whereas they are present in the female.

Figures

Fig. 1. Occurrence of Monodontium.

Fig. 5. Monodontium bukittimah, new species, holotype male: A, spinnerets, showing apical segment of PLS; B, tibia and metatarsus I, prolateral view; C, D, palp, distal tibia, tarsus and bulb, retrolateral view (C), prolateral view (D); E, palpal tibia, dorsal view; F, sternum, maxillae, labium and chelicerae; G, cephalothorax, dorsal view; H, tarsus; I, lateral view. Scale bars = 0.5 mm for F, G; 1 mm for rest.

Fig. 6. Monodontium bukittimah, new species, allotype female: A, cephalothorax, dorsal view; B, C, sternum, maxillae, labium and chelicerae; D, eyes; E, spinnerets; F, spermathecae. Scale bars = 1 mm for A, B; 0.5 mm for C; 0.2 mm for D, E; 0.1 mm for F.