Macrodactylus escuintlaensis Arce-Pérez & Morón, 2020

Arce-Pérez, Roberto & Morón, Miguel Ángel, 2020, Review of the species of Macrodactylus Dejean (Coleoptera: Scarabaeidae Melolonthinae) from the Central American Nucleus, Zootaxa 4772 (3), pp. 567-584 : 569-572

Macrodactylus escuintlaensis Arce-Pérez & Morón , new species

Figs. 2, 4, 9–11, 84

Material examined. ( 1 specimen ♂): Holotype male label: Guatemala: Escuintla, 1879, 1 ♂ [ MHNW].

Diagnosis. Integument of the body reddish black, clypeus, antennal flagellum, elytra, pygidium and legs reddish orange (apex of tibiae and tarsi darkened); dorsally glabrous, pygidium covered with short vestment; tarsi with rings of white setae (Figs. 2, 4); parameres long, oval, with long setae on the distal half and a wide notch externally near the apex (Figs. 9–10).

Figures 5–11. Diagnostic structures of Macrodactylus males and females. Parameres, distal view; parameres, lateral view; phalobase, dorsal view; genital plates, ventral view. 5–8, Macrodactylus eniocanoi Arce-Pérez & Morón , new species; 9–11, M. escuintlaensis Arce-Pérez & Morón , new species.

Description. Holotype Male: length 10.5 mm; humeral width 3.10 mm. Color: body black reddish, clypeus, flagellum, elytra, pygidium and legs reddish orange (apex of tibiae and tarsi darkened). Surface: dorsally glabrous, head and pronotum micropunctate; elytra with interstriae 2 and 4 slightly elevated; pygidium covered with short vestment, similar to venter; tarsi with rings of white, long setae (Figs. 2, 4). Head: long, micropuntate; clypeus trapezoidal, long, anterior border straight; antennal club black. Thorax: pronotum hexagonal, convex, length 2.75 mm, width 2.70 mm; prosternal process robust, long, apex strongly bifid (easily seen in frontal view); scutellum black, subtriangular and with sparse white setae. Elytra glabrous, with interstriae slightly elevated, with sutural and lateral margins darkened, base and suture with short and sparse yellow setae. Metasternum with two longitudinal rows of reddish yellow setae between mesocoxae and metacoxae. Legs: Profemur uniformly wide, with a concavity in the middle and a round projection on each side; Protibiae with long and thick setae in the inner basal region that is subtriangular in shape; Mesotibia widened towards apex, with two long spurs, the larger spur curved, with apex truncate; smaller spur straight and sharp. Tarsi long, with rings of white, long setae, all tarsal claws cleft. Abdomen: Sternites II–V moderately concave at middle, with three to four spine-like, long setae on each side of midline; pygidial plate elongate, oval, convex, with abundant, long reddish yellow setae. Genitalia: Length 2.75 mm (Fig. 11); parameres lange, oval, with long setae on the distal half and with slightly angulate outer margins, with a wide external notch near to the apex, completely fused dorso-basally, length 1.52 mm and width 1.02 mm; in frontal view the external border dorsobasally nearly straight (Figs. 9–10).

Figures 12–20. Dorsal view of Macrodactylus . 12, Macrodactylus carrilloi Arce-Pérez & Morón ; 13, M. costulatus Bates ; 14, M. championi Bates ; 15, M. dimidiatus Guérin-Méneville ; 16, M. fulvescens Bates ; 17, M. hondurensis Arce-Pérez & Morón ; 18, M. lineatocollis Bates ; 19, M. lineatus Chevrolat ; 20, M. montanus Arce-Pérez & Morón.

Geographical distribution. Known only from southern Guatemala (Fig. 84).

Etymology. This species is named M. escuintlaensis for the name of the department in which the specimen was collected: Escuintla, Guatemala.

Taxonomic comments. Macrodactylus escuintlaensis is included in the M. subspinosus species group (sensu Arce-Pérez and Morón 2000) because the clypeus is trapezoidal with anterior border straight; the metasternum has a row of long setae between the mesocoxae and metacoxae; mesotibiae with two long spurs, the larger spur curved and truncate and the smaller spur straight and acute; tarsi with rings of white setae; parameres long, oval, with long setae on distal half. Macrodactylus escuintlaensis is similar to Macrodactylus carrilloi Arce-Pérez & Morón but they differ [in square brackets Macrodactylus escuintlaensis ] because Macrodactylus carrilloi measures more than 11 mm length [10.5 mm], elytra with interstriae elevated [slightly elevated]; prosternal process with rounded apex [apex bifid]; profemur uniformly wide, with a subtriangular projection near to the base [profemur with a concavity in the middle and a round projection on each side]; parameres large, circular, with outer margins slightly rounded and a protuberance near the base [parameres long, oval, with outer margins slightly angulate and without protuberance].

This species was described based on a single specimen collected in the 19th century (1879). It is possibe that the characteristic of the dorsal surface (glabrous) may be different when fresh specimens are collected.