Acanthoscelides delgadoi Romero

Romero-Nápoles, Jesús, 2010, A New Species Of Acanthoscelides Schilsky, 1905 (Coleoptera: Bruchidae) From Nuevo León, Mexico, With A Key To The Obtectus Species- Group, The Coleopterists Bulletin 64 (2), pp. 125-128 : 126-128

Acanthoscelides delgadoi Romero , new species

Type Series. Holotype male, allotype female and paratypes: Nuevo León, Municipio Santiago, Paraje La Botella, por el camino Puerto Genovevo a Laguna de Sánchez , 1,100 m, Eduardo Estrada collector, 25°22 ′ 19 ″ N, 100°13 ′ 12 ″ W . Holotype, allotype, and two paratypes at the Florida State Collection of Arthropods ( FSCA), paratypes at Colección Entomológica del Instituto de Fitosanidad ( CEAM, 5♂ - 10♀), Colección Nacional de Insectos , Instituto de Biología , UNAM ( CNIN, 1♂, 3♀) .

Description. Male ( Figs. 1a – b ): Length (pronotum-elytra) 3.60 – 3.75 mm, width 2.34 – 2.40 mm. Maximum thoracic depth 1.86 – 1.89 mm. Integumental color: Body dark brown, except antennal segments I-IV or II-III red orange on their ventral face; pro- and mesotibiae with apices yellowish; bases of pro- and mesofemora sometimes yellowish. Vestiture: With recumbent white, goldenyellow, and light brown pubescence as follows: eye with medial fringe of golden-yellow setae; postocular lobe with short golden-yellow setae; postocular patch of dense golden-yellow setae; remainder of head with dense golden-yellow setae; pronotum with dense golden-yellow setae, underside with dense white setae; elytron with dense golden-yellow setae and contrasting subbasal, median, and apical dark brown patches, giving a variegated appearance; undersurfaces with dense white or intermixed white and golden-yellow setae; legs with moderately dense white or intermixed white and golden setae; pygidium with moderately dense to dense white or golden-yellow setae. Head. Short and broad, densely micropunctulate; frons with weak median carina; distance between eyes 0.77 to 0.83 times as wide as eye width; eye cleft 0.58 to 0.71 its length by ocular sinus; posterior margin of eye protruding from adjacent surfaces; postocular lobe rounded; distance from base of antennae to apex of labrum 0.44 to 0.49 times as long as distance from upper limits of eyes to apex of labrum; antennal segment 1 to 3 filiform, 5 to 10 eccentric, 11 acute apically; antenna extending slightly beyond humerus. Prothorax. Disk campanulate, foveolate; cervical sulcus shallow, extending from near coxal cavity to about 0.6 distance to pronotal midline; lateral prothoracic carina extending from base to 0.61 or to 0.76 distance to coxal cavity; without short median impressed line on median basal lobe; prosternum separating procoxae for 0.68 to 0.72 their length. Mesothorax and metathorax. Scutellum dark brown, quadrate, bifurcate at apex, clothed with white hairs; elytron about twice as long as broad; striae deep, punctate, strial intervals punctulate; striae 3 and 4, and 5 and 6 closer to each other at base than to adjacent striae, without denticles at their bases, stria 7 very abbreviate at base and 8 less abbreviate; humerus punctulate, glabrous, shiny black; undersurfaces and all of hind coxa punctulate, metepisternum coarsely foveolate. Legs. First and second protarsomeres subequal; first mesotarsomere about two times as long as second, first metatarsomere about three times as long as second; hind femur constricted basally and apically, expanded medially to about width of coxa; femur armed with subapical acuminate spine about 1.3 to 1.7 times as long as width of tibial base and 2 – 3 acuminate spines about 0.3 to 0.5 times as long as first spine; hind tibia with ventral, lateroventral, lateral and dorsomesal glabrous longitudinal carinae; tibial corona with 4 spinules, mucro 0.18 to 0.2 times as long as first tarsomere; without sinus at base of spine; first hind tarsomere with ventral and lateral glabrous longitudinal carina. Abdomen. First sternum not flattened medially, posterior margin straight, longer than remaining sterna; sterna 2 to 4 similar in size; fifth emarginate; pygidium punctate, convex in lateral view. Genitalia: Median lobe elongate; in ventral view ventral valve acute apically, lateral margins lightly concave; armature of internal sac with a dense cluster of fine spicules extending from near apex to near middle, and a basal spinescent structure ( Fig. 2a ). Lateral lobes elongate, apex of each lobe with transverse ventral sulcus where the apex of median lobe fits, cleft about 0.8 their length ( Fig. 2b ).

Female ( Figs. 1c – d ): Length (pronotum-elytra) 3.33 – 3.63 mm, width 2.25 – 2.40 mm. Maximum thoracic depth 1.62 to 1.8 mm. Similar to male, except antennae slightly shorter and fifth abdominal sternum not emarginate at apex.

Host Plant. Oxyrhynchus populneus (Piper) Norvell ex Delgado and Estrada (Fabaceae): Nuevo León, Municipio Santiago, Paraje La Botella, por el camino Puerto Genovevo a Laguna de Sánchez, 1,100 m, 7- XI- 2004, Eduardo Estrada 19262 a, 25 °22 ′ 19 ″ N, 100°13 ′ 12 ″ W.

Distribution. Mexico (Nuevo León).

Etymology. The specific epithet honors Dr. Alfonso Delgado Salinas, a botanist with long experience in studying legumes, particularly the genus Phaseolus L.

Diagnosis. Acanthoscelides delgadoi belongs to the obtectus species-group because the metafemoral mucro is 0.16 – 0.20 times as long as the first tarsomere, the elytra are vaguely variegated, and the overall similarity of the male genitalia with other species in the group. According to Johnson (1983, 1989, 1990), there are five species in the obtectus species-group. All of the known host plants in this group are in the legume subfamily Papilionideae. Acanthoscelides delgadoi is the largest species in the species-group. The sclerites in the internal sac are distinctive to this species, as well as the lateral lobes present at the apex of each lobe, and a transverse ventral sulcus where the apex of the median lobe fits.

Discussion. This is the first report of a bruchid host in the genus Oxyrhynchus Brandegee, however, according to Delgado-Salinas and Estrada Castillón (2009), the species populneus was transferred from Vigna Sabi to Oxyrhynchus. Oxyrhynchus populneus is a vine that may climb to 7 m long; the pods are dehiscent and with 5 – 6 seeds. I could not find any bruchid eggs on pods and seeds ( Figs. 3a, b ), so it may be that A. delgadoi belongs to the same oviposition guild as A. obtectus, that is, those species scattering eggs on pods and seeds.

Figures

Figs. 1–3. 1) Acanthoscelides delgadoi, a) Male dorsal view, b) Male lateral view, c) Female dorsal view, d) Female lateral view; 2) Acanthoscelides delgadoi, male genitalia, a) Median lobe, b) Lateral lobes; 3) Seeds of Oxyrhynchus populneus, a) Seed showing the emergency holes, b) Acanthoscelides delgadoi before leaving the seed.