Deltochilum acanthus Kohlmann & Solís, 2012

Kohlmann, Bert & Solís, Ángel, 2012, New species and revalidations of scarab beetles (Coleoptera: Geotrupidae: Athyreini and Coleoptera: Scarabaeidae: Scarabaeinae) from Costa Rica and Panama, Zootaxa 3193, pp. 28-52 : 36-38

Deltochilum acanthus Kohlmann & Solís , new species

Figs. 6 , 7 , 15

Diagnosis. This species is distinguished from other Costa Rican Deltochilum species by the following combination of characters: Pygidium with apex thickened, very acutely angled (90°) and outwardly produced ( Fig. 7 f). Apical half of metatibia bent inward.

Description. Holotype. Male ( Fig. 6 ): Length 11.9 mm. Humeral width 8.0 mm. Body color black, head and pronotum distinctly punctate.

Head approximately as long as wide; clypeus with two distinct, narrowly separated, upwardly reflexed, pointed teeth, pointed anterior teeth; each clypeal-genal margin with low obtuse teeth; vertex closely punctate, nearly flat; dorsal eyes large.

Pronotum with lateral margin angulate at middle, otherwise straight to slightly sinuate before and behind; pronotal surface densely punctate, giving the appearance of a honeycomb.

Elytral striae indicated by a double line, line expanded by widely separated, shallow strial punctures; disc intervals opaque, with numerous shallow, very close punctures ( Fig. 7 h); humeral umbone and apices of third to seventh intervals carinate; elytral surface shagreened. Epipleural upper carina interrupted ( Figs. 7 b, d).

Pygidium with apex thickened, very acutely angled and outwardly produced ( Fig. 7 f); disc nearly flat, shallowly and densely punctate, punctures umbilical. First abdominal sternite forms a rearward projection at the middle of the posterior border.

Profemur with margin unmodified; protibia with three apical teeth (the middle one smaller) and numerous serrations on outer margin. Apical half of metatibia bent inwardly.

Allotype. Female. Length 11.2 mm. Humeral width 7.6 mm. Similar to male, but the first abdominal sternite is evenly arched at the middle of the posterior border.

Variation. Fifty-eight specimens examined, 38 males and 20 females. Length 10.4–13.0 mm. Humeral width 7.3–8.0 mm.

Examined material (58 specimens). Holotype, male: COSTA RICA. Prov. Puntarenas. Res. Biol. Carara, Est., Quebrada Bonita. 50 m, jun 1993. J.C. Saborío. L-N-194500, 469850, CRI 001185073. Allotype, female: COSTA RICA. Prov. Puntarenas. R.B. Carara, Est. Quebrada Bonita. 50 m, nov. 1993. J.C. Saborío. L S 194500_469850, #2470, CRI 001969700. Paratypes. COSTA RICA. Prov. Puntarenas. Centro Juvenil Tropical. Alrededor de la Estación. 100m. 5–12 JUL 1997. M. Lobo. Colecta Nocturna. L_S_294700_517100 #47733, 1 female; Estación Esquinas, 0 m, Península de Osa, Abr 1993. M. Segura, L-S 301400_542200, 1 female; Estación Quebrada Bonita, 50 m, Res. Biol. Carara, 1 a 29 jul 1992, R. Guzmán, L- N 194500_469850, 1 male; Oct 1993. J. C. Saborío, L N 194500_469850 # 2396, 1 female; Set 1993. J. Saborío, L N 194500_469850 # 2354, 2 males; Nov 1993, R. Guzmán, L N 194500_469850 # 2447, 2 males; Jun 1993, R. Guzmán, L N 194500_469850 # 2202, 1 male; 2 a 23 set 1992, R. Guzmán, L-N 194500_469850, 3 males; agos 1993, R.M. Guzmán, L N 194500_469850 # 2297, 1 female; Ene 1994, R. M. Guzmán, L N 194500_469850 # 2572, 1 female; Feb 1994, R. M. Guzmán, L N 194500_469850 # 2613, 1 male; May 1994, R. M. Guzmán, L N 194500_469850 # 2914, 3 males, 1 female; Ago 1994, R. M. Guzmán, L N 194500_469850 # 3163, 1 female; Oct 1994. J.C. Saborío, Desconocido L_N_469850_194500 #3288, 1 female; Jun 1996. R. Guzmán. L_N_195250_469850 #7648, 1 male; Set 1994. R. M. Guzmán, L_N_194500,469850 #3214, 2 males, 1 female; May 1994. J. Saborío. L_N_470000_195200 #2849, 4 males, 1 female; Estación Sirena, 0–100m, P. N. Corcovado, Ago 1991, J. C. Saborío, L S 270500 _508300, 1 female; G. Fonseca, Jun 1991, L- S 270500 _508300, 1 male; Jun 1991, J. C. Saborío, L- S 270500 _508300, 1 male; Oct 1993. G. Fonseca, L S 270500 _508300 # 2380, 1 male; Jan 1990, G. Fonseca, L_S_ 270500 _508300, 1 female; G. Fonseca, Abr 1991, L- S 270500 _508300, 1 male, 1 female; G. Fonseca, Oct 1989, L- S 270500 _508300, 1 female; F. Quesada, Jun 1990, L- S 270500 _508300, 1 male; Refugio de Vida Silvestre Golfito, Estación Naranjales, 0 – 100m, 25 ABR 2004, W. Porras, Libre, L_S_289900_553450 #76842, 1 male; 22 – 27 ABR 2004, W. Porras, B. Gamboa, D. Briceño, M. Moraga, Amarilla, L_S_289900_553450 #76946, 2 males, 3 females; Rancho Quemado, 200 m, Península de Osa. 12 a 24 may 1993. A. Gutiérrez, L S 292500_511000, 1 male; Oct 1990. F. Quesada. L-S 292500,511000, 1 male; 11–28 Oct 1993, A. H. Gutiérrez, L S 292500_511000 # 2409, 2 males, 1 female; Río Agujas. Estación Agujas. Send. Ajo. 300m. 6–12 ENE 1998. M. Lobo. L_S_276750_526550 #49736, 1 male.

PANAMA. Canal Zone, Barro Colorado, Poscher’s Peninsula, 6 jun 1986. H. Wolda, 1 male; 11 jun 1986. H. Wolda, 1 female; 18 jun 1986. H. Wolda, 1 male; 25 jun 1986, H. Wolda, 1 male; 11 sep 1987. H. Wolda, 1 male.

Habitat. The species has been collected with flight interception traps in tropical rain forest, ranging from 0– 100 m altitude, during the months of April to November.

Geographical distribution ( Fig. 15 ). This species is known so far from the Pacific rain forest of Costa Rica and the Canal Zone of Panama.

Chorological affinities. Deltochilum acanthus seems to show a geographic vicariant pattern in relation to the similar species D. valgum acropyge , which inhabits the Caribbean slope of Costa Rica.

Taxonomic relationships. It would appear that the new species originated from a vicariant event, when the Talamanca range rose up approximately 3 million years ago, isolating the rain forest on the Pacific coast from the rainforests on the Caribbean coast. This mechanism seems to account for the origin of a great number of other animal vicariant species, examined in Kohlmann & Wilkinson (2007). We believe that D. valgum needs to be studied, and that its different subspecies represent a species complex in need of hierarchical revaluation. We therefore describe D. acanthus as a species and not as a subspecies, in anticipation of this process.

Deltochilum acanthus can be easily separated from D. valgum by its pygidium, which has the thickened apex, very acutely angled and outwardly produced ( Fig. 7 f), whereas D. valgum has a much less thickened and projected pygidium ( Fig. 7 e). There are also differences in dorsal punctation: the pronotum in D. acanthus is very densely punctured, producing the effect of a honeycomb, whereas in D. valgum the punctures are more spaced, by at least the length of one puncture. The elytral punctures are also different, in D. acanthus punctation is dense and the elytral striae are broad ( Fig. 7 h), whereas D. valgum is less densely punctured and the striae are thin ( Fig. 7 g).

Etymology. Acanthus (ĸανθοζ = acanthos), a Latinized Greek noun in apposition, meaning thorn, making reference to the spiny pygidial apex.

Figures

FIGURE 6. Dorsal view of a male Deltochilum acanthus Kohlmann & Solís, new species.

FIGURE 7. Side view of elytra (a, c) and pygidium (e) and dorsal view of left elytra (g) of Deltochilum valgum acropyge, and Deltochilum acanthus Kohlmann & Solís, new species (b, d, f, h). Carinae are delineated.

FIGURE 15. Known distribution of Deltochilum acanthus Kohlmann & Solís, new species (triangles) and Deltochilum valgum acropyge (circles). Base map from Google Maps.