Introduction

The tribe Anthonomini (Curculionidae: Curculioninae) contains more than 800 described species in 43 genera (^{Soto-Hernández et al., 2013}). Members of the tribe are associated with more than 35 plant families; however, for the majority of the described species the host plant are unknown (^{Anderson, 1993}). Anthonomus Germar, the best known and most diverse genus, contains more than 500 species described worldwide with the majority of the diversity found in the New World (^{Clark, 2014}). Species of Anthonomus are usually oligophagous; that is, each species feeds and develops on related species of plants in the same family. The Anthonomus squamosus species group contains 31 species in North America, which are characterized by the antenna with 7-jointed funicle and both the upper and lower surfaces of the body clothed with round to very elongate scales; which while dense in most of the species can be sparse and intermixed with a fine pubescence in some (^{Clark et al., 2019}; ^{Dietz, 1891}). Known host plants are species of Asteraceae and Malvaceae (^{Clark et al., 2019})

Although the Anthonomus squamosus group was revised quite recently, examination of collections has revealed an undescribed and distinctive species of Anthonomus best placed in this group. This species is here described as Anthonomus petrus Soto-Hernández n. sp.

Materials and methods

Morphological analysis and measurements were made with the aid of an ocular micrometer mounted in a dissecting microscope. Photographs were captured with a scanning electronic microscope JOEL, JSM 5600 L.V., and digital camera Nikon D7500.

Genital preparations were made heating dry specimens in water for some minutes to soften the tissues, after which the genitalia were removed from the abdomen, and heated in 10% potassium hydroxide solution (KOH) to disintegrate the fat and the soft tissues and subsequently in distilled water. The cleared genitalia were examined in glycerin using a stereomicroscope.

Specimens examined are deposited in the following collections: CMNC Entomology Collection, Canadian Museum of Nature, Gatineau, Canada; NHMUK The Natural History Museum, London, England; TAMU Insect Collection, Texas A&M University, College Station, Texas, USA; USNM United States National Museum, Washington DC, USA; UAQE Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, Mexico; CUCBA Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Mexico.

Description

Anthonomus petrus Soto-Hernández, new species (Figs. 1-8)

Figures 1-4 Habitus lateral and dorsal view. 1, 2) Anthonomus petrus male; 3, 4) A. petrus female. Scale = 1 mm. 

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Diagnosis: rostrum slightly expanded at apical 1/5, in both sexes with distinct elongate scales present beyond point of antennal insertion (Figs. 5, 6); scape longer than funicle and club combined; scutellum convex and triangular; and profemur with triangular tooth, sharply pointed and slightly curved toward tibiae.

Figures 5-7 Characters of Anthonomus petrus. 5) Rostrum, lateral view; 6) rostrum at 1/5, front view; 7) body scales finely striate. 

Body elongate-oval; length 2.1-2.4 mm, width 0.9-1.1 mm (n = 8) (Figs. 1, 2); integument reddish brown, densely covered with elongate acute and finely striate scales (Fig. 7), except head and thorax where lateroventral surface has broad, truncate scales each with apex feebly emarginate. Rostrum long, curved, ca. 1.7x longer than prothorax along dorsal midline, clothed with dense elongate, acute scales from base to very near apex, slightly expanded at about apical 1/5; lateral groove well defined, carinate. Antenna attached just beyond middle of rostrum; scape longer than funicle and club combined, apical margin strongly widened; funicle of 7 segments, segment 1 longer than 2, segment 2 shorter than 3 and 4 combined, segments 3-6 ca. 1.2x longer than wide, segment 7 strongly clavate; club elongate-oval, densely clothed with fine pubescence, as long as preceding 5 funicular segments combined. Head transversally with fine striate. Eyes slightly convex, smaller than width of rostrum at base in dorsal view. Prothorax ca. 1.3x wider than long, dorsal margin densely covered with elongate scales, intermixed with narrower and semierect scales, lateroventral surface clothed by truncate scales with apex slightly emarginate, scales broader than those on dorsum, anterolateral margin straight; sides slightly rounded. Scutellum convex, triangular, densely covered with slenderer, shorter and whiter scales than those on elytra. Elytra at base slightly broader than prothorax, densely covered with elongate, acute scales, intermixed with narrower, semierect ones, scales finely striate, each interstriae with row of semierect scales uniformly arranged; humeri present, rounded; pygidium covered by the elytra. Pro-, meso- and metasterna clothed with slightly broader and whiter scales than dorsum; procoxae contiguous, mesocoxae separated by ca. ½ width of coxa. Abdomen with scales narrower than those on mesosterna, abdominal ventrites convex, ventrites 3 and 4 slightly narrower than ventrite 5. Legs clothed with dense elongate, acute scales; profemur ca. 1.4x wider than metafémur, with triangular tooth, sharply pointed, slightly curved toward tibiae; tibiae with small mucro, scales narrower than on femur, protibiae with inner margin strongly sinuate, tarsal claw toothed, clothed with small sparse, fine setae, not obscuring integument. Aedeagus broad, symmetrical with sides subparallel, apex slightly acute (Fig. 8B-D); spiculum gastrale with plate bifurcate, sides slightly curved, apex progressively acute (Fig. 8F).

Figure 8 Genitalia of Anthonomus petrus, habitus lateral and dorsal view. A) Tegmen; B, C) aedeagus, habitus lateral and dorsal view; D) aedeagus apex, dorsal view; E) female genitalia, spermatheca; F, speculum gastrale plate and apodeme, dorsal view. Scale = 0.1 mm for A, B, C and F; scale = 0.05 mm for D and E. 

Female. Similar to male (Figs. 3, 4), except for the following characters: length 2.1-2.8 mm, width 1.0-1.2 mm (x̄ = 2.5, n = 10); rostrum long and slender, ca. 2.3-2.7x longer than the prothorax along dorsal midline; antenna attached just before middle of rostrum. Spermatheca as in figure 8E.

Remarks

Anthonomus petrus is easily recognized by the scales present on the rostrm beyond the point of antennal insertion. Aside from species of Narberdia Burke, I know of no other anthonomines with such large scales present beyond the point of antennal insertion. It apparently most closely resembles A. testaceosquamosus Linell but also differs in the pronotum with dorsomedian vittae of pallid ochreous scales, slightly darker ochreous scales in broad lateromedian vittae. In the Anthonomus squamosus species group, almost all species have the median lobe strongly attenuate at the apex (^{Clark et al., 2019}), while that of A. petrus is broad, slightly narrowed apically in dorsal view, very similar to A. curvicrus (Fig. 8C).