Macromalthinus quadratithorax Biffi & Constantin 2018, sp. nov.

Macromalthinus quadratithorax sp. nov.

(Figs. 5, 11, 17, 23, 29, 35, 41, 47)

Type material: HOLOTYPE: ♂: TRINIDAD AND TOBAGO. Trinidad, Simla, Arima, Blanchisseuse Rd., VII.1975, Blacklight trap, J. Price (NHMB) (Fig. 5). PARATYPES (4 ♀). TRINIDAD AND TOBAGO. Trinidad, W.I., S. Grande, Turure Rd., IV.1969, H & A Howden Collection (2 ♀ NHMB); Trinidad, W.I., Morne Bleu, 2700’, 15.VIII.1969, H & A Howden (1 ♀ NHMB); Trinidad, W.I., Morne Bleu, 2700’, 08.VIII.1969, H & A Howden (1 ♀ MZSP 35641).

Differential diagnosis: Pronotum subquadrate, entirely pale yellow; elytra greyish brown with yellowish to lightbrown apical patch; males: fore femur slightly swollen, with distinct, rounded ventral tooth; ventrite VIII without ridges; posterior margin notched at left side and acute tip; aedeagus with right prolongation of tegmen short;left setiferous prolongation short and wide, bearing thick, short apical setae; females: ventrite VII short, wide, lateral margins nearly parallel, posterior margin slightly projected.

Macromalthinus quadratithorax sp. nov. differs from the other northern South American species by having the pronotum subquadrate and greyish-brown elytra (the other species have pronotum strongly constricted near anterior angles and dark-brown to black elytra).

Description: Length: 5.7-6.4 mm. Colouration: Head black, frons and clypeus dark brown; antennae dark brown, antennomeres I-III testaceous ventrally, antennomeres IX-XI light brown; labium and maxillae light brown, labial and maxillary palpi testaceous to light brown; pronotum entirely pale yellow; elytra greyish brown, with a yellowish to light-brown apical patch; wings dark brown; legs pale yellow with dark-brown spots on the apex of femora dorsally, dorsal surface of tibiae and distal tarsomeres; thorax and abdominal tergites dark brown, abdominal ventrites light brown (Fig. 5).

Males: Head large, 1.3 times wider than the pronotum, temples elongate, strongly tapering posteriorly, vertex concave. Eyes large, oblong, very prominent. Antennae filiform, slender, covered with thin short setae; antennomere I elongate, II very short, 0.4 the length of I, III twice longer than II, IV-XI nearly same length as I. Pronotum (Fig. 11) subquadrate, 1.1 times wider than long; anterior margin slightly arched, lateral margins almost parallel, slightly constricted near anterior angles; pronotal surface elevated antero-medially and near posterior angles, forming a V-shaped shallow groove posteriorly. Elytra short, rugulose, densely covered with short and thin setae; sutures broadly dehiscent from posterior half; apex swollen dorsally. Legs slender; fore femur (Fig. 17) slightly swollen,with weak,rounded ventral tooth; femora,tibiae and tarsomeres increasing in length from fore to hind legs. Tarsal claws simple, not toothed. Abdominal tergites and sternites sclerotized; ventrites densely covered with long thin setae; glandular pores not prominent; distal margin of ventrite VI arched and slightly sclerotized; ventrite VII (Fig. 23) H-shaped, lateral margins sinuous, broader anteriorly, with broad membranous area anteriorly and deep posterior notch; ventrite VIII (Fig. 29) asymmetrical, oblong, strongly convex, without ridges; distal margin notched at left side, tip acute. Aedeagus (Fig. 35) with right prolongation of tegmen short, projected dorsally, without apophysis on its dorsal surface; left setiferous prolongation short, wide, bearing thick, short apical setae; right paramere elongate, slightly curved, with slight constriction near apex; left paramere elongate, narrow, flat, apex rounded; median lobe straight, broad, apex membranous. Measurements of holotype: TL: 6.0; AL: 4.8; OL: 0.51; HW: 1.12; IOW: 0.57; IAW: 0.2; PL: 0.86; PW: 0.93; EL: 1.8; EW: 1.24. Length of each antennomere: aI: 0.37; aII: 0.18; aIII: 0.30; aIV: 0.43; aV: 0.45; aVI: 0.47; aVII: 0.47; aVIII: 0.48; aIX: 0.48; aX: 0.43; aXI: 0.46.

Female: similar to male; eyes smaller, less prominent; fore femora slender, without intumescence or tooth; ventrite VI entire, not notched posteriorly; ventrite VII (Fig. 41) short, wide, lateral margins arched, slightly narrowed near angles, posterior margin slightly projected, strongly sinuous, forming two rounded lobes; base of coxites (Fig. 47) elongate, slender, apex very short, with short and broad projection behind styles bearing few thin setae; styles short, slightly wider apically, bearing thick setae. Measurements of medium size female paratype: TL: 5.6; AL: 5.12; OL: 0.55; HW: 1.15; IOW: 0.58; IAW: 0.21; PL: 0.87; PW: 0.97; EL: 1.70; EW: 1.22. Length of each antennomere: aI: 0.46; aII: 0.12; aIII: 0.38; aIV: 0.51; aV: 0.53; aVI: 0.53; aVII: 0.53; aVIII: 0.55; aIX: 0.52; aX: 0.47; aXI: 0.47.

Etymology: The specific epithet is derivative of the Latin words quadratus (square) + thorax (pronotum), referring to the shape of the pronotum in this species.

Distribution: Trinidad and Tobago (Fig. 66).