Prionus (Homaesthesis) geminus, Santos-Silva, Antonio, Nearns, Eugenio H. & Swift, Ian P., 2016

Santos-Silva, Antonio, Nearns, Eugenio H. & Swift, Ian P., 2016, Revision of the American species of the genus Prionus Geoffroy, 1762 (Coleoptera, Cerambycidae, Prioninae, Prionini), Zootaxa 4134 (1), pp. 1-103 : 34-36

Prionus (Homaesthesis) geminus sp. nov.

( Figs. 5–8 , 87–90 )

Prionus (Homaesthesis) integer ; Linsley, 1962: 51; Chemsak, 1996: 119.

Integument from reddish-brown to brown, with dorsal surface darker than ventral.

Male ( Figs. 87–88 ). Head, excluding mandibles, from slightly shorter to slightly longer at central area than prothorax, moderately elongate behind eyes (distance from posterior ocular edge to the prothorax slightly shorter than width of upper eye lobe). Longitudinal dorsal furrow distinct from clypeus to near prothoracic edge. Area between base of antennal tubercles and middle of upper eye lobes with sub-rhombus depression (sometimes slightly marked). Dorsal side of head coarsely, confluently punctate (sometimes almost smooth between eyes and prothorax centrally); with long, moderately abundant setae throughout. Area behind upper eye lobes, moderately coarsely, shallowly, confluently punctate; with long, moderately sparse setae; area close to eye with brush having long, abundant setae. Area behind lower eyes lobes moderately rugose, with sparse, long setae; area close to eye with brush having long, abundant setae. Antennal tubercles coarsely, confluently punctate at base, gradually finer toward middle, smooth toward apex; with long, sparse setae on base, anteriorly and posteriorly, centrally glabrous. Postclypeus laterally coarsely, abundantly punctate, gradually finely, sparsely punctate toward middle that is shallow or nearly so; with long, moderately abundant setae laterally, gradually shorter, sparser toward middle. Anteclypeus glabrous; anterior edge concave. Labrum centrally flat or depressed; with long, sparse setae; brush with long setae on anterior edge. Eyes proportionally large; distance between upper eye lobes equal from 0.75 to 1.00 times length of scape; distance between lower eye lobes from 0.65 to 1.10 times length of scape. Submentum trapezoid, slightly depressed; moderately coarsely, shallowly punctate-rugose; with long, moderately abundant setae. Apex of labial palpi nearly attaining middle of maxillary palpomere IV; apex of last maxillary and labial palpomere from 2.0 to 3.8 times as wide as its basal width. Mandibles from 0.45 to 0.65 times as long as head; latero-basal one-third distinctly depressed; narrow on lateral view; inferior outer margin usually sinuous; outer distal one-half distinctly curved, forming an obtuse angle with basal one-half (sometimes right angle). Antennae ( Figs. 6, 7 ) with 13 segments, sometimes with last segment fused with 12th segment; last segment from simple to slightly complex; attaining about middle of elytra. Scape slightly surpassing middle of upper eye lobe, not strongly enlarged toward apex; finely, sparsely punctate dorsally and laterally (more abundant on basal one-third). Antennomere III (including outer distal projection) from 1.6 to 1.9 times as long as scape, distinctly enlarged toward apex (distal width at apex of projection from 1.7 to 2.0 times basal width); on dorsal and ventral view, imbrication very distinct and projected ( Fig. 6 ); on lateral view, imbrication slightly emarginated ( Fig. 7 ); moderately finely, sparsely punctate dorsally. Antennomere IV from 0.6 to 0.7 times as long as III; moderately finely, sparsely punctate dorsally on inner side; imbrication as in III. Antennomeres V–VI with sculpture and imbrication as on IV. Antennomeres VII–XI/XII microsculptured dorsally; imbrication as in III.

Maximum prothoracic width from 0.65 to 0.75 times width of elytral base; anterolateral angle rounded; lateral tubercle placed between anterolateral angle and middle, acutely projected; posterolateral angle from acutely projected to slightly obtuse; margin between lateral tubercle and posterolateral angle from concave to sublinear; basal margin sinuous; distal margin from sublinear to sinuous. Pronotum moderately flat centrally, not strongly explanate laterally; callosities slightly marked; disc finely, abundantly punctate; moderately coarsely, abundantly punctate laterally; with long, moderately abundant setae throughout. Prosternum moderately finely, abundantly punctate (usually slightly rugose laterally); with long, moderately abundant setae. Prosternal process not longitudinally sulcate; with long, moderately abundant setae. Scutellum with long, moderately sparse setae (sometimes somewhat glabrous toward apex). Elytra coarsely, moderately abundantly punctate-rugose; each elytron with three carinae (sometimes outermost almost absent); with long, sparse setae near humerus laterally; remaining surface glabrous. Metasternum and metepisterna with long, abundant setae.

Ventrites I–II with long, moderately abundant setae (longer and more abundant on I); ventrite III–IV with long, sparse setae on basal one-half, with short sparse setae on distal one-half (sometimes absent, mainly on IV); ventrite V with moderately short setae, usually denser centrally, with long, sparse setae intermixed. Tarsomeres I–III moderately slender, not distinctly flattened; apices of tarsomeres I–III spined at apex (sometimes part of them just projected); pro- and mesotarsomeres I–III with spongy setal pads on ventral surface divided by distinct, moderately narrow glabrous longitudinal sulcus; spongy setal pads of metatarsi distinctly less dense than on pro- and mesotarsi; metatarsomere I from slightly shorter to as long as II–III together.

Female ( Figs. 89–90 ). Head, excluding mandibles, about as long as 0.8 times length of prothorax at middle. Sculpture on dorsal face of head and area behind eyes finer, distinctly sparser than in male. Distance between upper eye lobes from 0.7 to 0.8 times length of scape; distance between lower eye lobes from 1.0 to 1.3 times length of scape. Head, pronotum, scutellum, metasternum and metepisterna glabrous; prosternum with short, sparse setae; prosternal process mostly glabrous, with short, moderately abundant setae at apex. Antennae nearly attaining apex of basal one-third of elytra; scape more slender ( Fig. 8 ) than in male, from as long as to slightly longer than antennomere III, nearly attaining middle of upper eye lobe; antennomeres IV–XII with short imbrication, not emarginated centrally ( Fig. 5 ), not carinate ventrally. Prothorax as in male, but punctures usually finer. Metathorax distinctly shorter than in male.

Dimensions in mm (male/female). Total length (from mandibles to elytral apex), 19.0–23.5/22.3–24.2; prothoracic length at center, 2.8–3.8/3.6–4.0; greatest prothoracic width, 5.2–7.8/7.4–7.8; humeral width, 7.8–10.5/ 9.5–9.7; elytral length, 14.3–17.5/15.2–15.6.

Type material. Holotype male, from USA, Idaho: Pocatello (Bannock County), 20.VI.1973, G. W. Ulrich col. ( ESSIG). Paratypes—USA, Utah: Logan, 1 male, 3.VII.1937, G. F. Knowlton & W. P. Nye col. ( USNM). Idaho: Pocatello (Bannock County), 1 male, 3.VIII.1993, [no collector indicated] ( USNM); 1 male [identified as P. integer by Chemsak], 20.VI.1973, G. W. Ulrich col. ( ESSIG). Arizona: Williams, 1 male, 23–28.VII.1957, Neal McFarland col. ( MZSP). 1 male, 6 mi. E, Twin Falls, Twin Falls Co., IDA. 7-20-71, A.L. Antonelli collector ( ACMT).

Additional material examined (females—not paratypes). USA, Texas: Fort Stockton, 1 female, 15.V.1966, Michelb. col. ( ESSIG). Colorado: Fremont County, 1 female, 12.VII.1967, Scott col. ( ESSIG) [identified and figured as P. integer by Chemsak (1996)]. Colorado (?), 1 female, [no detailed place, date and collector indicated) ( USNM). 1 female, Star Lake, Lincoln Co. Ida., 7-15-59 ( ACMT).

Remarks. Prionus (Homaesthesis) geminus differs from P. (H.) emarginatus by the: imbrication of antennomeres in males slightly emarginated at apex (distinctly bifurcated in P. (H.) emarginatus ); last antennomere in males simple or slightly complex (distinctly complex in P. emarginatus ); ventral side of antennomeres in female not carinate (distinctly carinate in P. emarginatus ); apex of imbrication of antennomeres in female not emarginated at apex (emarginated in P. (H.) emarginatus ).

We have seen many specimens of this species identified as P. integer . In the key by Chemsak (1996) it can really be identified as P. integer , and his picture 7 of plate VIII correspond to this species, and not to LeConte’s species. In the key by Linsley (1962), some male specimens (mainly those with pronotal pubescence lost or partially lost) can also be identified as P. integer . However, the pronotal pubescence in true males of P. integer is absent or almost so on center of pronotum, and this is the most important feature that can be used to separate both species. Furthermore, the punctation on center of the pronotal disc in males of P. integer is distinctly finer than in P. geminus .

Since it was not possible to separate females of P. geminus from those of P. intege r with any confidence, we did not designate females of the former as paratypes.

Etymology. Latin, geminus = twin; relative to the similarity to P. (H.) emarginatus .

Figures

FIGURES 1 – 19. Antennae. 1 – 4, Prionus (Homaesthesis) emarginatus: 1, male, scape, pedicel, antennomeres III – V, dorsal view; 2, male, pedicel, antennomeres III – IV, latero-ventral view; 3, female, scape, pedicel, antennomeres III – IV, dorsal view; 4, female, antennomeres VI – VII, ventral view. 5 – 8, P. (H.) geminus sp. nov.: 5, female, antennomeres VI – VII, ventral view; 6, male, scape, pedicel, antennomeres III – IV, dorsal view; 7, male, pedicel, antennomeres III – IV, latero-ventral view; 8, female, scape, pedicel, antennomeres III – IV, dorsal view. 9 – 11, P. (H.) palparis: 9, male, scape, pedicel, antennomeres III – IV, dorsal view; 10, male, antennomeres III – V, ventral view; 11, female, scape, pedicel, antennomeres III – IV, dorsal view. 12 – 13, P. (H.) simplex, male: 12, scape, pedicel, antennomeres III – IV, dorsal view; 13, pedicel, antennomeres III – IV, ventral view. 14 – 16, P. (H.) spinipennis: 14, male, scape, pedicel, antennomeres III – IV, dorsal view; 15, male, pedicel, antennomeres III – VI, ventral view; 16, female, scape, pedicel, antennomeres III – IV, dorsal view. 17 – 19, P. (H.) arenarius, male: 17, scape, pedicel, antennomeres III – IV, dorsal view; 18, pedicel, antennomeres III – IV, latero-ventral view; 19, pedicel, antennomeres III – V, ventral view.

FIGURES 87 – 90. Prionus (Homaesthesis) geminus sp. nov.: 87, holotype male, dorsal habitus; 88, holotype male, ventral habitus; 89, female, dorsal habitus; 90, female, ventral habitus. Female specimen of the figures 88 and 89 was identified by John Chemsak as Prionus integer.