Pectinosoma Arrow, 1913

Katovich, Kerry, 2011, PseudopectinosomaKatovich, New Genus, and Review ofPectinosomaArrow (Scarabaeidae: Melolonthinae: Macrodactylini), The Coleopterists Bulletin 65 (4), pp. 335-340 : 335-340

Pectinosoma Arrow, 1913

Type Species. Pectinosoma elongatum Arrow 1913 .

Diagnosis. This genus is characterized by its elongate body and large size in comparison to most other macrodactylines; prementum elongate, ventral surface with a medial groove; mesosternum trapezoidal, flattened, anteriorly obscured in males by a posteriorly produced prothoracic process, fifth ventrite of males with a raised process, fused with tergite forming a solid, ring-like segment; visible in dorsal view; sixth ventrite partially concealed by pygidium; pretarsal claws simple in males, split in females.

Etymology. This genus in named for the unique comb-like abdominal process.

Pectinosoma elongatum Arrow, 1913 ( Figs. 3, 4 , 7, 8 , 11, 12 , 15, 16 , 19, 20)

Diagnosis. This species is recognized by its elongate body and large size (18 mm in length), black body color, white setae forming distinctive pronotal and elytral patterns; mesosternum of male anteriorly obscured by a posteriorly facing bifurcate prosternal process, posterior margin of process convex ( Fig. 7 ); fifth ventrite of male raised medially, posteriorly raised into a prominent trapezoidal process, process with distal margin lined with cylindrical, comb-like features, posterior margin grooved medially ( Fig. 8 ).

Material Examined. Holotype male, in BMNH: first label, round, red, Type H. T.; second label is a card with genitalia; third label small, white with green strip, Rotaima B. Guiana; fourth label small, white, Crowley Bequest 1901–78; fifth label large, white, Pectinosoma elongatum type Arrow (this label is in G. Arrow’ s handwriting). Four paratypes also in the BMNH, all males, with similar collection data. Two males in ZMNH with similar labels: first label, small, white, 20.4 – 5.5.88, Ig.N. Flauger, Venezuela Guaina, Gran Sabana; second label white, determination label, Pectinosoma elongatum Arrow 1913 , Det. K. Katovich. Single male in CMNC: first label Guayaraca, Auyantepui, BO, Venezuela, 1100 m 25-iv-56; second label F. Fernandez Y., C. J. Rosales, Cols.; third label H & A Howden Collection, ex. A. Martinez Coll.; fourth label Ancistrosoma male, ( Pectinosoma elongata (Arrow) , A. Martinez Det. 1978; fifth label Pectinosoma elongatum Arrow Det : A.B. T.Smith 2009. Single female in CMNC: first label Guayaraca, Auyantepui, BO, Venezuela, 1100 m 16-iv-56; second label F. Fernandez Y., C. J. Rosales, Cols.; third label H & A Howden Collection, ex. A. Martinez Coll.; fourth label Ancistrosoma female, ( Pectinosoma elongata (Arrow) , A. Martinez Det. 1964.

Redescription of Male. Modified from Arrow 1913: 430. Measurements (n = 5): Anterior ocular margin 2.0 mm; prothorax at apex 2.5 mm, at widest point 5.0 mm, elytra at base 4.0 mm, at widest point 8.0 mm, at declivity of elytral base 2.0 mm; total length 21.0 mm. Color and vestiture: Head and pronotum black, abdomen and elytra black, legs reddish brown, margins of elytra and pronotum lined with white setae. Head: Clypeus not coplanar with frons; frons angled at 30° in relation to clypeus; labrum in frontal profile narrow, rectangular, emarginate, not coplanar with clypeus; labium with prementum elongate, ventral surface with medial groove; mandibles in dorsal profile semicircular, scissoral area narrow, blunt, directed aborally, thin in lateral profile, well sclerotized, molar area produced aborally, well-sclerotized; maxillae with basistipes maxillary palpi with apical palpus ovate, equal to segments 2–3; antennae 9-segmented, segments 7–9 forming club, equal in length to segments 3–6 combined. Prothorax: Pronotum ( Fig. 11 ) oblong, longer than wide, widest at two-thirds distance from anterior margin, anterior angle acutely toothed, lateral margin convex, margin with slight bead in posterior third of margin, posterior angle obtuse, posterior margin weakly convex, margin with weak bead; prosternum ( Fig. 7 ) extending posteriorly over mesothoracic sternite, forming medially grooved, bifurcate process; prothoracic legs with transverse coxae; tibia widest in proximal fourth, weakly unidentate in distal fourth; pretarsus with claws not divergent, equal in length, claws simple in males. Mesothorax: Mesosternum trapezoidal, flattened, anteriorly obscured by bifurcate, posteriorly facing prosternal process, posterior margin convex; scutellum subtriangular, appearing weakly divided; elytra longer than wide, widest in anterior fourth, epipleuron with slight, deflexed margin, weak membrane along margin, elytral surface ( Fig. 12 ) lacking striae, anterior umbones prominent, posterior umbone weakly developed; pretarsus of midleg similar to that of proleg. Metathorax: Metathoracic coxae widely separated; leg with femur ovate, widest in distal fourth; tibia clavate, narrowed proximally; posteroventral margin with pair of spurs, ventral spur short, broad, dorsal spur elongate, narrow, spurs raised above level of tarsal articulation joint, posterior margin with several elongate setae, margin with deep, U-shaped groove; pretarsus of hind leg similar to those of proleg and midleg. Abdomen ( Fig. 8 ): First ventrite equal in width to combined widths of ventrites 2–3, fourth ventrite equal to width of ventrite 1, posterior margin medially concave, ventrites 2–4 with shallow medial depression, width of fifth ventrite equal to combined widths of ventrites 3–4, medially with a shallow depression, inside depression a raised, prominent, posteriorly facing, trapezoidal process, process with distal margin lined with 9 cylindrical shaped comb-like features, posterior half depressed, ventrite and sternite of fifth abdominal segment not separated by suture, spiracle placed anteriorly, sixth ventrite trapezoidal in ventral view, equal to width of fifth ventrite, flattened, in lateral view sixth ventrite partially concealed under pygidium; pygidium longer than wide, conical, with ventral surface formed by sixth ventrite. Genitalia: As in Figs. 19–20.

Redescription of Female. Measurements (n = 1): Anterior ocular margin 1.8 mm; prothorax at apex 3.0 mm, at widest point 6.0 mm, elytra at base 5.0 mm, at widest point 8.5 mm, at declivity of elytral base 2.0 mm; total length 17.0 mm. Color and vestiture: Head, pronotum ( Fig. 15 ), abdomen, and elytra ( Fig. 16 ) black, patches light brown, femora dark brown, tibiae and tarsi mottled brown, abdomen with fine yellow setae. In all other respects the females are similar to males, except that they lack abdominal processes, all claws are split, and the sixth ventrite is narrowly rectangular. The pygidium is not as triangular as in the male and its posterior margin is sinuate.

Distribution. This species is recorded from Guyana and Venezuela (new country record).

Remarks. The immature stages of this species remain unknown, as does its habitat.

Etymology. This species is named for its very elongate body.

Figures

Figs. 1–4. 1–2) Pseudopectinosoma mesa, male, dorsal and lateral views; 3–4) Pectinosoma elongatum, male, dorsal and lateral views.

Figs. 5–8. 5) Pseudopectinosoma mesa, male, procoxae and pro- and mesosternum, ventral view; 6) P. mesa, male, visible abdominal segments, ventral view, membranous posterior margin of sixth ventrite shaded gray; 7) Pectinosoma elongatum, male, procoxae and pro- and mesosternum, ventral view; 8) P. elongatum male, visible abdominal segments, ventral view.

Figs. 9–12. 9) Pseudopectinosoma mesa, male, head and pronotum, dorsal view; 10) P. mesa, male, scutellum, elytra, and pygidium, dorsal view; 11) Pectinosoma elongatum, male, head and pronotum, dorsal view; 12) P. elongatum, male, scutellum, elytra, and pygidium, dorsal view.

Figs. 13–16. 13) Pseudopectinosoma mesa, female, head and pronotum, dorsal view; 14) P. mesa, female, scutellum, elytra, and pygidium, dorsal view; 15) Pectinosoma elongatum, female, head and pronotum, dorsal view; 16) P. elongatum, female, scutellum, elytra, and pygidium, dorsal view.