Scrapter pruinosus Davies, 2006

Davies, Gregory B. P. & Brothers, Denis J., 2006, Morphology of Scrapter (Hymenoptera: Anthophila: Colletidae), with description of three new species and taxonomic status of five Cockerell taxa, African Invertebrates 47, pp. 135-183 : 166-170

Scrapter pruinosus Davies , sp. n.

Figs 86 , 103–109

Etymology: Latin pruinosus (frosty, covered in hoar-frost or ice). In allusion to the characteristic vestiture of this bee that affords it a frosted appearance ( Figs 103, 104 , 105 ).

Diagnosis: A tiny bee characterised by its distinctive ‘hoar-frost’ vestiture, yellowish mandibles, bright yellow legs, and partially red T1–3. Further features include fairly dense (^) to very dense (ơ) mesoscutum punctation, lack of a clypeal sulcus, tuberculate metabasitibial plate (^), deeply cleft claws and narrow facial foveae (bottom of fovea visible).The ơ S. pruinosus keys out to S. avius Eardley ; it may also exit at S. caesariatus Eardley (because of the thick vestiture on the tergal discs), but the reddish metasoma, lack of reticulate sculpture on the mesoscutum, and half-entire (as opposed to entire) metabasitibal plate are diagnostic characters. The ơ S. pruinosus is strikingly similar to S. avius but the dense metasomal vestiture is characteristic, the terminalia are distinct (see Eardley 1996, figs 32–34 for S. avius ) and S. avius does not have a reddish metasoma. The ^S. pruinosus keys to S. avius but the thick, white vestiture on the mesoscutum and metasoma of S. pruinosus is distinctive. Further T2–4 is all orange in S. avius but banded black and orange in S. pruinosus , and the prepygidial fimbria in S. avius has some black hairs (all white in S. pruinosus ).

Description:

Male.

Measurements (n =4): total body length 5.9 mm, head length 1.5 mm, head width 1.8 mm, lower interocular distance 1 mm, upper interocular distance 1.3 mm, interanntenal distance 0.4 mm, antennocular distance 0.2 mm, length of clypeus 0.6 mm, length of eye 1.2 mm, length of facial fovea 0.4 mm, maximum width of facial fovea 0.04 mm, mesoscutum length 1 mm, mesosoma length 2 mm, forewing length 3.9 mm, length of pterostigma 0.6 mm, maximum width of pterostigma 0.1 mm, length of marginal cell beyond pterostigma 0.8 mm, length of marginal cell 1.1 mm, length of free-part of marginal cell 0.7 mm, metatibia length 1.2 mm, metabasitarsus length 0.7 mm.

Vestiture: With the naked eye, the frosty-white, short vestiture is immediately striking and distinctive. Clypeus, supraclypeal area and lower paraocular areas completely obscured by dense, white, decumbent, minutely plumose (‘bristly’) hairs. Frons, vertex, upper paraocular area with sparse, erect, white hairs (integument easily discernible). Mesoscutum, scutellum and metanotum thickly covered in short, decumbent to suberect, short, stout, bristly hairs. Sides of mesosoma with fairly dense, white, bristly vestiture. Tergal discs thickly covered in short, dense, decumbent, bristly, white hairs, most of integument not visible. T6 and T7 hairs longer and more golden. Sternal discs have very sparse, longish hairs (contrasting notably with tergal vestiture).

Integumental colour: Principally black bar metasoma and legs. Protibia and protarsi bright yellow (protibia with pale brownish patch anteriorly). Apical end of profemur orange-yellow. Mid- and hind-leg with similar colour pattern.Antenna brownish above, bright yellow below (on F2–5 dorsal brown patches reduced, most of flagellomere yellow). Mandibles apically black, basal 2/3 yellow. T1, T2 and T3 with posterior band along marginal zone orange-red, remainder of tergal segment black. T4 and T5 mainly black. All sterna orange-yellow.

Head (Prosoma): Clypeus heavily punctate (interspace <0.5× puncture diameter), narrow interspaces smooth and shiny, no medio-longitudinal clypeal sulcus, ventral margin of clypeus slightly emarginate. Supraclypeal area weakly elevated with dense punctation. Frontal line barely evident. Facial fovea sharply-defined, narrow, shiny and smooth. Paraocular area and frons densely punctate.Inner eye orbits diverging dorsally, proportion of lower to upper interocular distance 0.8:1. Antenna rather short, just reaching tegula. Labrum longer than broad. Basal area of labrum smooth and elevated with medial protuberance, apical area of labrum hairy.

Mesosoma: Lateral ridge of pronotum not strongly elevated but narrow-edged. Oblique lateral sulcus of pronotum well-developed, terminating dorsad of pronotal ridge. Mesoscutum heavily punctate (interspace <0.5× puncture diameter), narrow interspaces smooth and shiny. Median line moderately impressed, notaulus barely evident. Scutellum and metanotum sculpture similar to mesoscutum. Propodeum angulate. Propodeal triangle basal area with sharply-defined, irregular, mostly longitudinal carinae; interspaces roughened. Mesepisternum smooth, shiny and densely punctate (interspace <0.5–1× puncture diameter). Pre-episternal groove strongly impressed, pitted throughout. Legs: Metabasitibial plate only with posterior carina present. Pretarsal claws deeply cleft.

Metasoma: Tergal discs smooth, shiny and densely punctate. T2 fovea ovoid. Pygidial plate absent.

Terminalia: Gonobase large, inner margin of gonocoxite toothed, gonoforceps divided into two surfaces by medial, longitudinal ridge; outer surface concave and moderately hairy, inner surface undistinguished, rather flat with few hairs ( Fig. 106 ). Penis valves long, narrow and slightly exceeding gonoforceps in length ( Fig. 106 ). Ventrally gonoforceps with large ventral process ( Fig. 106 ). Well-defined digitus and cuspis in volsella ( Fig. 106 ). S6 weakly emarginate posteriorly with broad field of hairs ( Fig. 107 ). S7 simple in form, weakly emarginate posteriorly forming two points ( Fig. 108 ). S8 posterior region elongate, posterior plate sub-truncate, posterior process fairly hairy ( Fig. 109 ).

Female.

Measurements (n =4): total body length 6.9 mm, head length 1.7 mm, head width 2.1 mm, lower interocular distance 1.3 mm, upper interocular distance 1.4 mm, interanntenal distance 0.4 mm, antennocular distance 0.4 mm, length of clypeus 0.6 mm, length of eye 1.3 mm, length of facial fovea 0.6 mm, maximum width of facial fovea 0.03 mm, mesoscutum length 1.2 mm, mesosoma length 2.3 mm, forewing length 4.5 mm, length of pterostigma 0.7 mm, maximum width of pterostigma 0.2 mm, length of marginal cell beyond pterostigma 1.0 mm, length of marginal cell 1.2 mm, length of free-part of marginal cell 0.7 mm, metatibia length 1.4 mm, metabasitarsus length 0.9 mm.

Vestiture: Generally similar to ơ. Face thick, white, bristly hairs (especially dense on paraocular area and frons). Vertex sparse, erect, white hairs. Gena dense, appressed, bristly, white hairs (integument largely obscured). Mesoscutum, scutellum and metanotum thickly covered in short, erect, bristly hairs (integument not completely obscured, though). Sides of mesosoma similar but longer, sparser hairs. Metasomal terga with very dense, white, short, bristly vestiture largely obscuring integument. S1 and S2 with long, plumose, white hairs forming fairly thick scopa. Remaining sterna with a few plumose hairs, but vestiture weak. Sparse brush on anterior (outer) surface of probasitarsus composed of simple and branched hairs. Metatibial scopa and prepygidial fimbria all white.

Integumental colour: Mainly black, posterior third of T1–5 bright orange. S2–4 orange, S5–6 dark orange-brown. All tibia and tarsi yellow-orange, but metadistitarsus dark orange-brown. Apex of pro- and mesofemur yellow-orange. Undersides of antenna yellow.

Head (Prosoma): Clypeus smooth, shiny, dense punctation (interspace about 0.5× puncture diameter), no medio-longitudinal clypeal sulcus. Supraclypeal area weakly elevated with dense punctation. Paraocular area and frons with dense punctation, smooth interspaces. Facial fovea narrow and smooth. Labrum longer than broad, elevated basal zone with medial protuberance. Glossa apex weakly emarginate. Galeal comb comprising approximately 12 teeth. Maxillary palp slightly exceeding galeal apex in length (last two palpomeres protruding).

Mouthparts: Weakly bilobed glossa with strong glossal brush. Maxillary palp quite long, slightly exceeding galea apex. Labial palp short, falling short of glossa apex.

Mesosoma: Lateral ridge of pronotum rather weakly developed, narrow-edged. Oblique lateral sulcus of pronotum well-developed, terminating dorsad of pronotal ridge. Mesoscutum fairly dense to dense punctation (interspace about 0.5–1× puncture diameter). Scutellum and metanotum similar mesoscutum. Mes- and metepisterna fairly dense to dense punctation, smooth interspaces. Propodeum angulate. Propodeal triangle basal area with longitudinal carinae and roughened interspaces.

Legs: Metabasitibial plate reduced to very short, posterior carina basally and about 6 small tubercles delineating outline of plate ( Fig. 86 ). Pretarsal claws deeply cleft, preapical tooth slightly shorter than outer tooth.

Metasoma: Tergal discs smooth, shiny and heavily punctate. T2 fovea ovoid. Pygidial plate smooth, parallel-sided, rounded apically.

Terminalia:T7 with strongly produced apodemal region, posterior edge almost straight, spiracle placed far back but not opening onto posterior edge, lateral lamina narrow (approximately 0.1× breadth of lamina spiracularis). Dorsal arm of furcula approximately 0.5× length of ventral arm.Apodemal ridge of 2 nd gonocoxa straight. Gonoplac parallelsided, hairy apically.

Holotype: ơ NAMIBIA: Lüderitz (26°35'S: 15°07'E), 7.xii.1994, M. Kuhlmann ( SANC).

Paratypes: 11ơ and 10^with same label data as holotype (all MKPC, except 1^in SANC) .

Distribution: S. pruinosus is only known from the type locality of Lüderitz, which is a town at sea-level in southern Namibia. The Lüderitz area is a harsh, hyper-arid environment with cold buffeting Atlantic winds and a sparse, dwarf shrubland vegetation. Lüderitz falls near the northern edge of Succulent Karoo biome (and winter rainfall zone).

Biology: There are no relevant floral records.

Figures

Figs 86–88. Metabasitibial plates of Scrapter bees: (86) female S. pruinosus sp. n.; (87) female S. nitidus; (88) Anterior view of metabasitibial plates: (A) female S. armatipes, (B) male S. capensis, (C) female S. tomentum, (D) male S. algoensis. Abbreviations: MetPl – metabasitibial plate margin entire, Tubs – tubercles delimiting edge of metabasitibial plate.

Figs 103, 104. Lateral views of Scrapter pruinosus sp. n. male (103) and female (104).

Fig. 105. Dorsal view of female Scrapter pruinosus sp. n.

Figs 106–109. Scrapter pruinosus sp. n., terminalia: (106) genitalia (dorsal and ventral views), (107–109) S6–8. Scale bar = 0.4 mm.