Macrodactylus tibialis Arce­Pérez and Morón, Arce-Perez and Moron, 2005

Arce-Pérez, Roberto & Morón, Miguel-Angel, 2005, New species and new records of species of Macrodactylus Dejean (Coleoptera: Scarabaeidae: Melolonthinae: Macrodactyini) from Honduras and Nicaragua, Zootaxa 1012 (1012), pp. 23-37: 29-31

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Macrodactylus tibialis Arce­Pérez and Morón

new species

Macrodactylus tibialis Arce­Pérez and Morón   , new species

( Figs. 7,10, 13–15)

Diagnosis. This species is distinguished by the following combination of characters: antennal club unicolored; pronotum, elytra, and pygidium glabrous, orange; tarsi without rings of white setae; male with a strong, acute spine near the middle of the inner border of each protibia; parameres are stout without setae on the external borders.

Description. Holotype. Male: Body length 12.5 mm; humeral width 3.5 mm. Color ( Fig. 7): clypeus, antennae, mouthparts, pronotum, elytra, pygidium, last sternite, femora, and tibiae orange; frons, scutellum, pterothorax, abdomen, and tarsi black. Surface: dorsally glabrous with iridescent silky shine when viewed without magnification, coarsely punctate or finely rugose with magnification; ventrally with short, fine, yellow setae. Head: clypeus trapezoidal, anterior border nearly straight; antennal club yellow; mentum elongate, longitudinally furrowed, anterior border straight, anterolateral emargination exposing basal segment of labial palpus. Thorax: pronotum hexagonal, convex, 3.1 mm length, 2.8 mm width; prosternal process small, subtriangular, slightly depressed, hidden in frontal view; scutellum elongate with rounded apex; elytra with punctate striae. Metasternum with two longitudinal rows of short, red setae between meso­ and metacoxae. Procoxa conical, prominent. Protibia with two rounded teeth at the apex of external border and one strong, acute spine near the middle of inner border ( Fig. 1). Protibial articulated spur absent. Protarsus shortened, with spine­like setae at the apex of each segment, without rings of white setae. Meso­ and metafemur with short, spine­like setae scattered on ventral surface. Mesotibia widened toward the apex with two long, narrow, straight, acute spurs and long spine­like setae around the apex. Metatibia widened toward the apex with some preapical long, black setae on the inner surface, and long, spine­like setae around the apex. Meso­ and metatarsi enlarged with short, spine­like setae on the surface and long spine­like setae around the apex of each segment, without rings of white setae. All tarsal claws narrowly cleft. Abdomen: sternites 2–4 moderately concave at middle with two spine­like, erect, reddish, short setae at the sides of midline; length of sternite 5 twice the length of sternite 4 with numerous spine­like, erect, long setae near the posterior border; sternite 6 ovate, with numerous spine­like, red setae on the surface and long, black setae on the apical border. Pygidium elongate, strongly convex, with scattered spine­like setae. Genitalia: total length 3.75 mm; parameres stout, glabrous, completely fused dorsobasally, widely curved toward the apex, forming an oval in distal view with 1.50 mm length and 1.24 mm width; each apex weakly lanceolate ( Figs. 13–14).

Allotype. Female: Body length 12.0 mm; humeral width 3.9 mm ( Fig. 10). Similar to male except as follows: pronotum 3.05 mm length, 3.10 mm width; protibia without acute spine near the middle of inner border with preapical articulated spur; abdominal sternites 2–4 convex at middle without erect, long setae; pygidium short, weakly convex, nearly triangular. Genital plates large, external border widely curved ( Fig. 15).

Variation (131 paratypes). Body length 12.0– 13.5 mm; humeral width 3.0– 3.6 mm; prosternal process slightly elongate in some specimens; pronotum completely dark green or orange with a dark green stripe along the midline or a dark brown spot at the middle of pronotal disc in some specimens from Nicaragua. Posterior half of the elytra iridescent dark brown in some specimens from Honduras.

Material examined (79 males, 57 females). Holotype male: NICARAGUA. Km 137 carretera Matagalpa­Jinotega , 1000 m, 1 July 1984, on weeds along the road, Col. J. M. Maes ( IEXA)   . Allotype female: NICARAGUA. Matagalpa department, Fuente Pura , 1500 m, 9 July 1995, on Zea mays, Cols. J. M. Maes & P. Jolivet (IEXA)     . Paratypes: same data as holotype (1 male) ( MXAL)   ; same data as allotype (2 males) ( MELN)   ; same data except: 12 June 1994, Cols. J, M. Maes, J. Téllez & J. Hernández (1 male) ( MXAL) (1 female) ( MELN)   ; 26 June 1994 (1 male, 1 female); 6 July 1994, Cols. J. M. Maes & J. Hernández (1 male) ( MELN)   ; NICARAGUA. Matagalpa department, Selva Negra , 1300 m, 8 May 1995, Cols. J. M. Maes, J. Téllez & J. Hernández (1 male, 7 females) ( MELN)   ; Matagalpa, Selva Negra (hotel) 25–29 June 2004, Col. P. Schoolmeesters (2 males, 1 female) ( PSPC)   Madriz department, Somoto, San Lucas , 1370 m, 29 July 2000, Cols. J. M. Maes & B. Téllez (1 male, 1 female) ( MELN)   ; Jinotega department, Cerro Kilambe, Camp. 2, 1550 m, 10/ 17 May 1998, Cols. J. M. Maes & B. Hernández (3 males, 1 female) ( MELN)   ; 9 km E Jinotega, Finca Santa Enriqueta , 1250 m, 24/ 30 May 2003, Col. D. Roiz (6 males, 3 females) ( MELN)   ; 5 km S Jinotega, Los Pinares , 1500 m, 29 May 1992, Cols. J. M. Maes & C. Pineda (1 male) ( MELN)   . HONDURAS. El Paraiso department, Yuscarán , 1030 m, 8 June 1994, on Pouteria sapota, Cols. H. & A. Howden & B. Gill   (53 males, 31 females) ( HAHC, BDGC, EAPZ, IEXA, MXAL)   ; Cerro Monserrat , 7 km SW Yuscarán, 1800 m, 8 June 1994, Cols. H. & A. Howden & B. Gill (3 males, 10 females) ( HAHC, BDGC)   . Olancho department, La Muralla, 24 May 1995, Col. R. Morris (1 male) ( HAHC)   ; P. N. La Muralla , 24/ 27 May 1995, Col. J. E. Wappes (1 male) ( HAHC)   .

Biology. This species inhabits montane moist forests located at altitudes from 1000 to 1800 m. Months of collection: May (24), June (101), July (8). Specimens were collected on Pouteria sapota   L. ( Sapotaceae   ) in El Paraiso department, Honduras and on Zea mays   L. ( Poaceae   ) and unidentified weeds at Matagalpa department, Nicaragua.

Geographical distribution. Mountains in the southeast of Honduras and northwest of Nicaragua, Central America (13°– 15° N, 86°– 87° W) GoogleMaps   .

Taxonomic comments. Macrodactylus tibialis   is the only known species in this genus with an acute spine on the inner border of the male protibia. It is included in the “ M. dimidiatus   ” group (sensu Arce­Pérez and Morón, 2000) because the dorsal surface and pygidium are glabrous and lack the scale­like setae typical of other groups of species, the tarsal segments do not have rings of white setae, the parameres are stout and are without setae on the external borders, and the genital plates of the females are large with the lateral borders widely expanded.

Etymology. The Latinized name refers to the sexually dimorphic structure of the protibia in this species.


Escuela Agricola Panamericana


Departamento de Geologia, Universidad de Chile