Pachycerus vestitus, (FAHRAEUS, 1842)

Meregalli, Massimo, 2009, Revision of the Indo-African Pachycerus Schoenherr, 1823, with a description of four new species (Coleoptera: Curculionidae: Lixinae), Zoological Journal of the Linnean Society 157 (2), pp. 295-325 : 306-309

PACHYCERUS VESTITUS ( FÅHRAEUS, 1842)

Cleonus vestitus Fåhraeus, 1842: 49 .

Pachycerus vestitus: Chevrolat, 1873: 110 . Pachycerus vestitus: Faust, 1904: 223 .

Cleonus (Pachycerus) vestitus: Csiki, 1934: 54 . Cleonus (Pachycerus) vestitus: Alfieri, 1976: 255 .

Lectotype (designated here), probably male (not dissected): 1. W. Abiad [?] 1837 (hw); 2. Bahr el Abiad (pr); 3. ‘85’ (pr); 4. ‘3.’ (pr); 5. Hdb (pr); 6. Type (red, pr); 7. Cleonus vestitus Fåhraeus, 1842 , Lectotypus, 2007 Meregalli des. (NHRS, coll. Schoenherr, drawer #187).

Other specimens: Sudan: ‘ Kordofan , Bedel’, 1 ♀ ( SMTD) ; Senegal: ‘ Senegal, Richter’ , 1 ♂ ( SMTD) ; ‘ Seneg’ , 1 ♀ ( BMNH) ; Guinea: ‘ Guinea’ , 1 ♂ ( BMNH) .

Type: The name vestitus probably comes from Schoenherr, whose acronym ‘Schh.’ is cited by side of the epithet, before the diagnosis; the description is signed by Fåhraeus. The description (Fåhraeus, in Schoenherr, 1842: 49) reads ‘ Patria: Bahr el Abiad Aegypti. Dom. Hedenborg. Mus. Reg. Ac. Scient. Holm.’ One specimen is preserved in NHRS, and is labelled Bahr el Abiad. The original description gives no hint of the number of specimens seen by Fåhraeus, thus the specimen preserved in NHRS is designated here as the lectotype of C. vestitus .

Measurements: Body length excluding rostrum: 10.29 mm. Rostrum: length, 2.05 mm; width, 1.03 mm; ratio, 2.00. Pronotum: length, 2.48 mm; width, 3.14 mm; ratio, 0.79. Elytra: length, 6.60 mm; width, 4.36 mm; ratio, 1.51. Ratio of elytral to pronotal length: 2.66 (♂; Guinea).

Redescription ( Figs 43–56 ): Body oblong-elliptical, of medium size, integument dark reddish, thickly covered with bifid scales and long setae ( Figs 43–44 ). Rostrum strong, subquadrate in transverse section, dorsolateral margins moderately raised, straight, parallel from base to apex, median line raised, obtusely convex, widened forwards, epistoma angularly convex at middle, apex prominent; dorsum weakly impressed between central and dorsolateral margins; in lateral view rostrum nearly straight from base to antennal insertion, curved downwards apically, distinctly thickened from base to apex; upper margin of scrobes straight, not keeled, reaching base of eyes; lower margin shortly directed to underside of rostrum; scrobes wide, broadened from antennal insertion to base, and glossy; vestiture extremely thick, completely hiding surface, composed of long, light-yellowish scales, bifid from base, very dense, moderately erect, imbricate, centripetal to forward-directed on dorsum, also very dense on dorsal keel, where they are often simple, relatively broad, long acuminate; beyond antennal insertion scales simple, long, acuminate, outward-directed, and semi-erect; dorsolateral margins with a row of hair-like setae, erect, and slightly longer than the scales; epistoma with some very long, erect, forwarddirected setae; sides in front of eyes with few setae, upward oriented and very scarce simple scales, not hiding the glossy, punctured integument; underside with long, slender setae moderately raised ( Figs 45– 46 ). Antennae short, densely scaly; scape distinctly curved forwards, moderately thickened from base; funicle thick, compact, of uniform thickness, segment I subcylindrical, as long as wide; segments II–VII progressively more transverse; club long elliptical, acuminate, segment I subcylindrical, thick also at base, densely scaly in its basal half, finely hairy as the rest of club in apical half ( Fig. 47 ). Head moderately larger than rostrum, strongly delimited from base of rostrum, vertex distinctly raised laterally above eyes, flattened on centre, base behind eyes impressed; vestiture extremely dense, on vertex with narrow acuminate simple scales, directed backwards, above eyes with tufts of dense raised short lightbrownish setae. Eyes elongate, oblique, weakly convex, dorsal margins parallel. Pronotum small, transverse, base weakly oblique, centre not sharply protruded towards elytra, sides straight, nearly parallel from base to apical quarter, shortly converging at apex; apex weakly rounded above head, postocular lobes distinct; dorsum on disc with a shallow longitudinal broad impression; surface densely punctured, with deep round punctures delimited by narrow raised interspaces, sculpture hidden by vestiture; sides lacking distinctly raised glossy granules; vestiture composed of generally bifid, rarely simple, light- and dark-brown scales, forming a sharp pattern: light-brown scales disposed in a broad stripe in the central longitudinal impression, in two narrow curved dorsal lines, starting near centre at apex, outwards curved up to behind middle of length, rectilinearly narrowed at base, and in a broad dorsolateral stripe, sharply delimited and straight in its lower margin, corresponding with the maximum width of pronotum, and angularly expanded towards dorsum, joined to dorsal narrow lines in their external point; dark-brown scales cover integument on remaining places; setae narrow, semi-erect, with the same colour as adjacent scales, and relatively densely inserted over the whole pronotum ( Fig. 48 ). Scutellum very narrow, and scarcely distinct. Elytra long and oval, at base slightly broader than base of pronotum; weakly broadened at humeri, sides subrectilinear up to near apex, and shortly convergent at apex; in lateral view regularly curved from base to apex, with declivity not sharp but distinct; odd intervals moderately convex, wider than even intervals and wider than striae, intervals 3 and 5 higher and curved at base; even intervals narrow, flat; striae broad, composed of dense seriate round punctures, larger in basal half and progressively narrowed towards apex; integument smooth, lacking granules or deep wrinkles; vestiture composed of bifid light- and dark-brown scales ( Fig. 56 ), and long, erect setae, light- and dark-brown in distinctive patterns: dark-brown scales dense and uniform on interval 3 from base to declivity, dense on intervals 5 and 7 from base to apex, but interrupted by light transverse stripes, and on suture at base; light-brown scales in patches on declivity and interval 2 from near base to apex, on intervals 9 and 10 forming a lateral stripe from base to apex; on basal half forming a broad transverse curved stripe, broadened laterally, starting from suture, interrupted on interval 3, and joined to the lateral stripe; on declivity forming a broad transverse stripe; base on intervals 4–8, and median part of elytra between the two transverse light stripes, excepting on intervals 3 and 5, nearly devoid of scales, with a few scattered darkbrown scales and a few round spots of white scales; setae semi-erect and of same colour as neighbouring scales, on intervals 3, 5, and 7 longer than interval width, dense, arranged in two or three rows, on even intervals shorter, usually arranged in a single row. Legs strong, very densely scaly and with very long setae, scales usually simple, slender, and light brownish; femora scarcely thickened at middle; fore tibiae strong, moderately widened from base to apex, apex not broadened, with strong denticles; middle and hind tibiae stronger; fore tarsi short, segment I not longer than wide, shortly triangular, segment II triangular, as long as wide, segment III short, lobes scarcely developed, onychium nearly as long as segments I–III together; claws strong, connate at midlength, and widely separate; hind tarsi only moderately longer than fore tarsi; underside lacking an adhesive pad, replaced by a few whitish simple scales, with some spiny setae on sides. Ventrites with segment I as long as segment II, together longer than segments III–V combined, segment III as long as segment IV, segment V slightly longer than segment IV, transverse, flat; vestiture composed of extremely dense bifid light-brownish scales and frequent long, semi-erect setae ( Fig. 51 ). Aedeagus tubular, slender, median lobe long, moderately curved, apical lamella shortly triangular ( Figs 50, 53, 55 ). Sternite VIII of female with apodeme nearly as long as lamina, arms broadened, sclerotization limited to apical part of lamina ( Fig. 52 ); spermatheca with curved, moderately narrowed cornu; nodulus shortly thickened, ramu short, lateral ( Fig. 54 ). Hemisternites globose, apical shortening very close to neck; styli cylindrical, obliquely cut ( Fig. 49 ).

Variation: The few specimens examined are relatively uniform. Those with complete vestiture have a slightly variable distribution of light- and dark-brown scales; however, the two transverse broad light stripes delimiting a dark-brown patch are always distinct. The length of the setae on the elytra is variable; the specimens from West Africa have longer setae. The size ranges between 9.2 and 10.3 mm.

Affinities: The very long, semi-erect setae on the elytra allow an immediate distinction of P. vestitus from all the other species of the genus. Based on the vestiture, the form of the scales, i.e. long, bifid, and with very divergent teeth, and the shape of the rostrum and the pronotum, this species seems to be more closely related to P. sellatus than to the other species of the genus.

Distribution ( Fig. 108 ): The type locality, Bahr el Abiad, indicates the river also known as the White Nile, one of the chief tributaries of the Nile, which extends upstream from Khartoum to the junction of the Bahr el Jebel and the Bahr el Ghazal at Lake No, c. 160 km above Malakal, in present-day Sudan. Pachycerus vestitus appears to have a disjunct range in the Sahel, and the specimens from West Africa appear to be moderately differentiated; however, the available material is too scant to allow any further discussion about a possible taxonomic vicariance of the West African population: one of the very few specimens seen originates from Kurdufan, in central Sudan, whereas the others are from Guinea and Senegal. Alfieri (1976) cited the species generically for Egypt (‘Recorded for Egypt’, Alfieri, 1976: 255), without further details, but so far it has not been recorded for the present-day territory of Egypt.

Figures

Figure 108. The Indo-African species of Pachycerus. Distribution map. Map taken from Encarta World Atlas 2000 (Microsoft Corporation), refined with Photoshop 7.0.

Figures 43–56. Pachycerus vestitus Faust, 1904, lectotype: body (43, 44); rostrum (45, 46); pronotum (48). Pachycerus vestitus, Guinea, male: antenna (47); detail of elytral scales (56); ventrites (51); aedeagus (50, 53, 55). Pachycerus vestitus, Kordofan, female: sternite VIII (52); hemisternite (49); spermatheca (54). Scale bar: 43, 44, 5 mm; 51, 2 mm; 45, 46, 48, 50, 1 mm; 47, 49, 52, 53, 0.5 mm; 54, 55, 0.2 mm.