Macrodactylus oaxacaensis Arce-Pérez & Reynoso, 2021

Arce-Pérez, Roberto & Reynoso-Velasco, Daniel, 2021, Two new species of Macrodactylus (Coleoptera: Scarabaeidae: Melolonthinae Macrodactylini) from Mexico and Guatemala, Zootaxa 4903 (4), pp. 493-500 : 497-499

Macrodactylus oaxacaensis Arce-Pérez & Reynoso , new species

(Figs. 9–10, 13–17)

Type series. HOLOTYPE ³. MEXICO: Oaxaca, Municipio San Miguel Suchixtepec, 8 km south of Suchixtepec , 6.VIII.1986, H. & A. Howden ( CMNC) . ALLOTYPE: same data as holotype (1♀ CMNC) . PARATYPES (3³, 10♀): same data as holotype (2³, 7♀ CMNC; 1³, 1♀ IEXA) ; same data as holotype except 10.VIII.1986 (2♀ CMNC) .

Diagnosis. Integument of the body, head, pronotum, and scutellum black; elytra, pygidium, trochanters, femora, tibiae, and tarsi reddish yellow; head, pronotum, and scutellum with slight greenish-yellow reflections, and minute, white vestiture; elytra glabrous; tarsi with rings of long, white setae (Figs. 9–10); parameres almost circular, lateral setae subapically, with lanceolate apex (Figs. 13–14).

Figures 13–16. Genital structures of the male and female of Macrodactylus oaxacaensis new species. 13, Male parameres, posterior view; 14, male parameres, lateral view; 15, male phallobase, dorsal view; 16, female genital plates, posterior view. Scale bars in 13–14 = 0.30 mm, 15 = 0.77 mm, and 16 = 0.31 mm.

Description. Holotype. Male: Body length 12.12 mm; humeral width 3.70 mm. Color: body, head, pronotum, and scutellum black; antennae bicolored; elytra, pygidium, trochanters, femora, tibiae, and tarsi reddish yellow (Figs. 9–10). Surface: head, pronotum, and scutellum with light greenish-yellow reflections and minute vestiture of white setae; elytra glabrous; ventrally with long, yellow-gray vestiture; pygidium with vestiture similar to that of the venter. Head: elongate; clypeus trapezoidal, punctate, with anterior border slightly concave. Thorax: pronotum hexagonal, convex, length 3.00 mm, width 2.70 mm; prosternal process short, cylindrical, apex rounded (not easily visible in frontal view); scutellum subtriangular; elytra glabrous with six lightly imprinted longitudinal striae, not costate (Fig. 9). Metasternum broad, with two longitudinal rows of long, spine-like setae between the mesocoxae and metacoxae. Legs: profemur with an elongate, laminar projection near the base; mesotibiae widened toward the apex, with two spurs, one large spur curved apically and the small spur straight; tarsi with rings of long, white setae; all tarsal claws cleft. Abdomen: robust, sternites 2–5 moderately concave (lateral view), with four or five spine-like, slender setae on each side of midline; pygidial plate elongate, oval, convex, with vestiture similar to that of the venter. Genitalia: total length 3.10 mm (Fig. 15); parameres length 1.22 mm, width 1.04 mm, stout, almost circular (posterior view), with long and short lateral setae subapically, completely fused dorsobasally, each apex broadly lanceolate (Figs. 13–14).

Allotype female: Similar to male except for: body length 11.25 mm; humeral width 3.70 mm. Pronotum length 2.75 mm, width 2.75 mm; abdominal sternites convex (lateral view), reddish black, with slender, scattered, reddishyellow setae; pygidium short, subtriangular, slightly convex. Genital plates large, subrectangular, length 1.24 mm, width 0.48 mm, lateral margin almost straight (Fig. 16).

Variation: Body length 10.00–11.00 mm; humeral width 3.50–4.00; anal plate with some red coloration; elytra with small, fine, scattered setae.

Geographical distribution. This species is distributed in the southern Mexican state of Oaxaca (Fig. 17). The type locality (8 km south of Suchixtepec) is in the Sierra Madre del Sur biogeographic province .

Figure 17. Distribution of Macrodactylus miguelangeli new species (yellow squares) and Macrodactylus oaxacaensis new species (red circle).

Natural history. This species inhabits a mountain forest at an elevation of 2400 m and was collected during August.

Etymology. The specific epithet derives from Oaxaca, the Mexican state where this species was collected.

Comments. Macrodactylus oaxacaensis is included in the M. subspinosus species group (sensu Arce-Pérez & Morón 2000) because it has the clypeus with the anterior margin sinuate; the metasternum with a row of long setae between the mesocoxae and metacoxae; the mesotibiae have two long spurs, with the large spur curved near the apex and the small spur straight; the tarsi have rings of white setae; and the parameres are almost circular, with setae near the apex of the lateral margins. Macrodactylus oaxacaensis is similar to M. montanus Arce-Pérez & Morón, 2000 , but they can be distinguished because the former has glabrous elytra (Fig. 9) [with pale-yellow vestiture in M. montanus (Figs. 11–12)], tarsi dark apically (Fig. 10) [completely yellowish red in M. montanus (Fig. 12)], tarsi with rings of long setae (Fig. 10) [rings of short setae in M. montanus (Fig. 12)], and parameres without a ridge on the internal margin (a conspicuous ridge on the internal margin in M. montanus ) and with long and short lateral setae (Fig. 13) (medium size setae in M. montanus ).