Prionacalus White, 1845

Santos-Silva, Antonio, Komiya, Ziro & Nearns, Eugenio H., 2013, Revision of the Genus Prionacalus White, 1845 (Coleoptera: Cerambycidae: Prioninae: Prionini), The Coleopterists Bulletin 67 (3), pp. 201-240 : 205-208

Prionacalus White, 1845

Prionus (Prionacalus) White 1845: 109 .

Prionacalus ; White 1853: 7; Gemminger and Harold 1872: 2754 (catalogue); Monné and Giesbert 1994: 14 (checklist); Monné 1995: 60 (catalogue), 2006: 82 (catalogue); Martínez 2000: 80; Di Iorio 2003: 2; Monné and Hovore 2005: 19 (checklist), 2006: 18 (checklist); Monné et al. 2012: 7 (checklist).

Prionocalus; Chevrolat 1847: 469; Thomson 1861: 297, 331, 1864: 280, 468, 1877: 252, 260; Lacordaire 1868: 41; Waterhouse 1872: 261 (key to species); Quentin and Villiers 1983: 223, 225 (key to species); Hüdepohl 1985: 120 (key to species).

Psalidognathus (Prionocalus) ; Lameere 1910: 374, 1913: 65 (catalogue), 1919: 121; Blackwelder 1946: 555 (checklist).

Type Species. Prionus (Prionacalus) cacicus White, 1845 (monotypy).

Redescription. Medium (ca. 24 mm) to large (ca. 74 mm) size, variable intraspecifically. Integument from slightly opaque to shining, brown to blackish brown, frequently with reddish parts.

Male. Head: Prognathous, large ( Figs. 16 , 27 , 40 ), excluding mandibles 1.2–1.6 times longer than prothorax; very elongate behind eyes (distance from posterior ocular edge to prothorax 2.2–3.7 times width of upper ocular lobe). Longitudinal dorsal exuvial cleavage line (coronal suture) usually not well-marked, often visible only behind eyes, occasionally absent. Vertex almost flat at base, gradually oblique towards middle of antennal tubercle, then abruptly becoming steeper (frequently distinctly vertical or bent inwards) towards clypeus (centrally usually less elevated when longitudinal furrow is deep) (this latter area would correspond to region of frons); coarsely, abundantly punctate, frequently also partially granulate, mainly laterally; usually with 2 cephalic carinae between upper ocular lobes, from antennal tubercle to about middle of area behind eyes (sometimes shorter), occasionally absent; with short, sparse setae. Area between cephalic carinae flat to distinctly depressed; frequently with shallow to deep, short (not reaching middle of eyes) to long (slightly surpassing posterior ocular edge) longitudinal furrow, occasionally almost absent. Antennal tubercle very distinct; apex rounded, turned sideward; bases of tubercles ranging from subcontiguous (separated only by the longitudinal furrow) to widely separated (distance between them about twice its width). Frontal sutures and frons usually indistinct. Epistomal suture usually laterally well-marked, often less so centrally (occasionally absent centrally). Clypeus with 2 areas: basal area subhorizontal, distal area not coplanar with basal area, usually from strongly oblique to vertical, in some species distinctly concave. Basal portion of clypeus narrow (centrally 0.20–0.25 times width between tentorial pits), flat, centrally on basal 2/3 usually slightly obliquely elevated (occasionally not elevated, but with 2 gibbosities); glabrous or with sparse, very short setae; sculpture variable: coarsely, shallowly, abundantly punctate, or moderately finely, sparsely punctate, or almost smooth; anterior edge widely emarginate. Distal portion of clypeus smooth (sometimes with very sparse fine punctures), shining, glabrous. Labrum from narrow (length about 0.25 times width) to wide (length about 0.40 times width); at least basal area oblique in relation to distal region of clypeus; frequently strongly depressed centrally on distal area; distal area coplanar or not with basal area; distal edge straight or slightly convex or, more rarely, slightly concave (sometimes centrally feebly projected); surface shining, smooth, glabrous (sometimes with long, sparse setae); distal edge centrally with long setae (occasionally along nearly entire edge). Anterior tentorial pits well-marked. Eyes narrow (width equal to about 0.3 times length), finely faceted, distinctly emarginate, moderately small; ocular lobes with same width; upper ocular lobe a little shorter than lower ocular lobe; distance between upper ocular lobes 2.3–4.2 times longest width of 1 lobe; apex of lower ocular lobes reaching level of middle of mandible at base. Lateral area of head, behind eyes, with 1 tubercle, intraspecifically variable in size (from moderately small to large) and shape (from distinctly acute at apex to rounded); surface usually roughened, with short, sparse setae between level of tubercle and prothorax (occasionally, with some sparse setae between level of tubercle and eyes). Genal apex usually with downward projection (small or absent in some species; in others always very distinct). Gula trapezoidal (occasionally, length equal to about 0.4 of total length of ventral surface); with short, abundant setae on base, sparser towards apex. Posterior tentorial pits well-marked. Gular sutures well-marked, deep. Submentum moderately well-delimited (sometimes distinctly delimited), usually depressed from gula to near anterior 1/3 where distinctly elevated; sculpture variable; with short, sparse setae (often almost glabrous). Mandible intraspecifically variable in size and shape (variation usually linked to size of specimen), but always long and apically curved downward and inward; left mandible different in form from right one; coarsely, abundantly punctate, with short sparse setae (except on apical portion). Mentum transverse (longest length about 0.35 times width); anterior margin trilobed (central lobe occasionally very short or absent); about as wide as 1/2 width of submentum at anterior margin; coarsely, moderately abundantly punctate (sometimes only laterally); with long, moderately sparse setae. Galea very short, reaching from about middle to distal 1/3 of palpifer, with long, abundant setae turned upwards. Palpifer, with distal membra- nous area not extended, about as long as maxillary palpomere I. Maxillary palp very long (1.2–1.3 times anterior width of head); palpomere I shorter than remaining segments, II longer than III, and IV longer than others; palpomere IV strongly enlarged towards apex. Ligula bilobed, each lobe obliquely projected forward. Labial palp very long (1.0–1.2 times anterior width of head); palpomere I 0.5–0.7 times length of II, and palpomere III slightly longer than II; palpomere III strongly enlarged towards apex. Antennae with 11 segments; almost reaching to distinctly surpassing elytral apex; scape conical or slightly enlarged towards apex, distinctly surpassing posterior ocular edge, shorter than antennomere III, at least dorsally coarsely punctate; pedicel very small (smaller than 0.2 times length of antennomere III) to small (slightly longer than 0.2 times length of antennomere III); antennomere III longest, enlarged towards apex, ventral surface with or without sensorial area near apex (if present, not divided by carina); ventral surface of antennomere IV with sensorial area on distal 1/2, divided or not by carina, and sometimes with small dorsal sensorial area; ventral surface of antennomere V almost entirely occupied by sensorial area, always divided by at least 1 carina (frequently more), dividing sensorial area into irregular areas, and sometimes with small dorsal sensorial area; ventral surface of antennomeres VI-XI entirely occupied by sensorial area, always divided by longitudinal carina, and dorsally with sensorial area (larger and divided by carinae from VII or VIII); basal antennomeres with short, sparse setae (usually only at apex), and distal antennomeres glabrous (occasionally, antennomere XI with very short, sparse setae on apex). Thorax: Prothorax transverse (longest width 1.9–2.6 times central length); latero-anterior angle slightly projected forwards, latero-posterior angle from projected sideward (frequently almost as a spine) to rounded; lateral edges with spines (sometimes almost coarsely crenulate); anterior edge from straight to somewhat rounded (not rarely centrally emarginate); posterior edge from slightly sinuate to rounded. Pronotum convex, centrally depressed, and laterally expanded; surface coarsely rugopunctate; centrally glabrous (occasionally with some setae), and laterally with short, sparse setae. Prosternum convex, strongly elevated centrally; surface usually striate (sometimes coarsely) and finely, sparsely punctate; with short, sparse setae (sometimes almost glabrous). Prosternal suture distinct, straight from procoxal cavity towards apex. Procoxal cavities widely opened posteriorly. Prosternal process long, reaching basal 1/3 to middle of mesocoxae. Mesosternum narrow, separated by complete sutures from mesepisterna. Mesocoxal cavities laterally open. Mesepisternum with or without short setae. Mesosternal process deeply sulcate (sometimes less so), narrowed towards apex. Metasternum reduced; surface moderately finely punctate to coarsely punctate; with short, sparse setae. Metepisternuma with margins parallel at basal 3/4 and convergent at distal 1/4 (inner margin more distinctly), or slightly curved at inner margin, mainly at distal 1/2; surface abundantly or moderately coarsely punctate, with short, sparse setae. Scutellum short, transverse, rounded or moderately straight distally, and emarginate or not at center of this edge (variable intraspecifically); surface from finely to coarsely punctate (variable intraspecifically), and short and moderately abundantly setose or almost glabrous (intraspecifically variable). Elytra fused at suture; outer margin parallel at basal 1/3 or 1/2, distinctly convergent in remainder; humeral angle situated below level of scutellar apex, usually strongly spiniform; elytral surface, behind humeral spine, usually abruptly sloping downward; apices usually individually rounded (occasionally almost truncate, and sutural angle sometimes projected); glabrous or with very short and sparse setae at base; surface entirely coarsely rugose (somewhat vermiculate) or finer rugose on distal 2/3; membranous wings ( Fig. 36 ) very small (about 0.2 times length of elytron). Abdomen: Occasionally surpassing elytral apex, narrowed from base to apex, strongly convex at ventrite I, gradually becoming flatter towards apex; ventrite I longest, II slightly longer than III, III and IV with subequal length, V distinctly emarginate at apex. Median lobe of genitalia 1.2–1.4 times length of tegmen; ventral lobe of distal portion of median lobe distinctly narrowed towards apex, not surpassing apex of dorsal lobe; dorsal lobe of distal portion of median lobe distinctly emarginate at apex; basal apophysis of median lobe enlarged towards apex, 0.65–0.75 times total length of median lobe; lateral lobes of tegmen 0.25–0.30 times total length of tegmen, with long, dense setae on dorsal distal 1/2 (occasionally only at distal 1/3), distinctly sparser on basal 1/2 (occasionally only at basal 1/3), ventral surface and lateral margins with long, dense setae. Legs: Trochanter with elliptical depression ventrally, coarsely, sparsely punctate (sometimes abundantly punctate), with long, sparse setae (sometimes shorter or more abundant). Femora narrower dorsally than ventrally, dorsally convex, laterally oblique, and ventrally sulcate; pro- and mesofemora subequal in length, metafemora distinctly longer; lateral surface transversely rugose and punctate (variable in shape and concentration), usually coarsely on profemora; apex of metafemora usually surpassing elytral apex (sometimes only reaching elytral apex). Protibiae distinctly swollen centrally, narrow at base, apex somewhat narrower than middle area, distinctly compressed dorso-ventrally on distal 1/5 or 1/6; latero-distal surface with moderately abundant denticles (sometimes with distinct spines on margin), usually with distinct depression near apex, ventral surface longitudinally deeply sulcate (length of depression variable), with dense setae in depression; apex with 2 spurs (the lower is longest). Meso- and metatibia enlarged from base to apex, usually with small spines and denticles on proximal surface (sometimes absent on metatibiae or both), depressed on distal 1/3 or 1/4 of proximal surface (depression occasionally distinct from basal 1/3, but always more conspicuous distally; sometimes almost inconspicuous); apex with 2 spurs, inner most larger. Tarsi long, mainly meso- and metatarsi; protarsi moderately enlarged (occasionally slightly more than mesotarsi); mesotarsi slender and longer than protarsi, and metatarsi slender and longer than mesotarsi; metatarsomeres I-III usually spined at apices (less distinctly on protarsomeres).

Female. The main differences with males are as follows: mandibles shorter than head; last segment of palpi (maxillary and labial) less expanded towards apex (usually 0.5–0.65 times longest width of male); antennae shorter, never reaching elytral apex; elytra usually more rounded from base to apex; elytra sometimes not fused at suture; protibiae ventrally not sulcate, not swollen centrally; apex of metafemora not or rarely reaching elytral apex; abdomen usually surpassing elytral apex; apex of ventrite V from truncate to slightly emarginate (sometimes rounded).

Included Species. Prionacalus atys White, 1850 ; Prionacalus cacicus (White, 1845) ; Prionacalus demelti Quentin and Villiers, 1983 ; Prionacalus iphis White, 1850 ; Prionacalus uniformis Waterhouse, 1900 ; Prionacalus whymperi Bates, 1892 ; and Prionacalus woytkowskii ( Heyrovsky, 1960) .

Geographical Distribution. Ecuador, Peru, Colombia, Bolivia, and Argentina.

Diagnosis. Prionacalus is similar to Psalidognathus . Males differ as follows: length of head (excluding mandible) + prothorax 0.70–0.75 times elytral length (0.40–0.45 times in Psalidognathus ); brachypterous (membranous wings well-developed in Psalidognathus ); metasternum distinctly shortened (not shortened in Psalidognathus ). Females differ as follows: body, in lateral view, wider (body narrower in lateral view in Psalidognathus ); two anterior spiniform projections on lateral margins of prothorax usually broadly joined and occasionally strongly protracted (two anterior spiniform projections on lateral margins of prothorax distinctly separated and more strongly protracted in Psalidognathus ). Prionacalus differs from Apterocaulus by the body less flattened dorsoventrally, the dorsal surface of the head usually with two carinae, the mid-lateral spiniform projection of the prothorax shorter and not strongly curved backwards, and the distinctly narrower tarsi. In Apterocaulus , the body is flatter dorso-ventrally, the dorsal surface of is head lacks carinae, the mid-lateral spiniform projection of the prothorax is distinctly longer and strongly curved backwards, and the tarsi are distinctly shorter and wider.

Remarks. All species of Prionacalus exhibit notable allometry in the proportions of the head, size and shape of the mandible, palpi, antennae, and elytra. The considerable number of specimens with features intermediate among the species suggests that hybridism may occur. A phylogenetic analysis including both morphological and molecular data is needed to test this hypothesis.

Figures

Figs. 16–26. Prionacalus atys. 16) Male, dorsal view; 17) Male, ventral view; 18) Male, head, dorso-lateral view; 19) Male, mandibles; 20) Male, protarsus; 21) Male, mesotarsus; 22) Female, metatarsus; 23) Female, dorsal view; 24) Female, ventral view; 25) Female, mandibles, 26) Female, metatarsus.

Figs. 27–39. Prionacalus cacicus. 27) Male, dorsal view; 28) Male, ventral view; 29) Male, head, dorso-lateral view; 30) Medium sized male, mandibles; 31) Small male, mandibles; 32) Male, protibia; 33) Male, protarsus; 34) Male, metatarsus; 35) Male, mesotarsus; 36) Male, wing; 37) Female, dorsal view; 38) Female, ventral view; 39) Femle, metatarsus.

Figs. 40–50. Prionacalus demelti. 40) Male, dorsal view; 41) Male, ventral view; 42) Male, head, dorso-lateral view; 43) Male, mandibles; 44) Male, protarsus; 45) Male, mesotarsus; 46) Male, metatarsus; 47) Female, dorsal view; 48) Female, ventral view; 49) Female, mandibles; 50) Female, metatarsus.