Polynoncus pittinoi Costa-Silva & Diéguez, 2020

Costa-Silva, Vinícius & Diéguez, Víctor Manuel, 2020, A new species of Polynoncus Burmeister (Coleoptera: Trogidae) from Argentina, Zootaxa 4868 (2), pp. 267-274 : 268-270

Polynoncus pittinoi Costa-Silva & Diéguez , new species

Figs. 1–7 .

Type specimens. Holotype (male, MACN): First label [white, typeset]: “ARGENT. CORDOBA / Depto. Calamuchita [Santa Rosa de Calamuchita city] / [Hotel] El Sauce. Diciemb. 1973 / leg. Manuel Viana ”. Second label [red, handwritten]: “ Polynoncus pittinoi ♂ / Costa-Silva & Diéguez / HOLOTYPE ” ( Fig 7 ). Condition of holotype: both antennal clubs are missing. 2 Paratypes labelled as follows: one female specimen ( CEMT): First label [white, handwritten]: “Arg—Córdoba / [Villa] Yacanto / x.1970. M. Viana ”. Second label [yellow, handwritten]: “ Polynoncus pittinoi / Costa-Silva & Diéguez / PARATYPE ♀ ”. One female specimen ( CJEB): First label [white, handwritten]: “Arg—Córdoba / Río Tercero / x.1970. M. Viana ”. Second label [yellow, handwritten]: “ Polynoncus pittinoi / Costa-Silva & Diéguez / PARATYPE ♀ ”.

Differential diagnosis. Polynoncus pittinoi is externally similar to P. gemmifer (Blanchard, 1847) ( Figs. 8–11 ), P. burmeisteri Pittino, 1987 ( Figs. 12–15 ), and P. haafi ( Vaurie, 1962) but can be easily separated by the presence of yellow setae in the antennae, propleuron and legs, which is black in the other three species. Polynoncus pittinoi can be confused with Polynoncus neuquen ( Vaurie, 1962) ( Figs. 16–19 ), because both have antennae with yellow setae. However, the crenulate lateral margin of pronotum (which is smooth in P. pittinoi ) and the small and flat elytral tubercles can separate P. neuquen from the new species (compare the elytral tubercles in Fig. 1 and Fig. 16 ). The male genitalia are distinctive between all species ( Figs. 5–6 , 10–11 , 14–15 , 18–19 ).

Description of holotype. Size: Length: 9.75 mm, width: 6.13 mm ( Fig. 1 ).

Colour: Black, with shiny elytral tubercles. Body with irregular velutinous patches ( Figs. 1, 2, 4 ).

Head: Clypeus with the apex deflexed at right angles to the clypeal disc; deflexed portion triangular, apex pointed; posterior margin of clypeus emarginate in dorsal view ( Fig. 1 ). Eyes large and bulbous, barely visible in dorsal view. Antennal scape dark brown, with long, yellow setae; pedicel with one row of long setae all around; surface sparsely punctate, punctures of equal size (barely visible in dirty specimens). Genae angulate, pointed laterally. Frons with two bulbous median tubercles; tentorial pits deep.

Pronotum: About 1.7 times wider than long, slightly narrower than elytra; sides broad, flat; pronotal surface sparsely punctate, punctures shallow and variable in size. Anterior angles acute, distinctly projecting forward. Posterior margin widely projecting backwards. Lateral margin smooth, attenuate anteriorly with sparse, yellow setae. Pronotal disc raised with two barely visible median longitudinal ridges extending over anterior 2/3 of pronotum; median depression shallow. Median basal tubercles obsolete; laterobasal tubercle broad, only slightly raised. Anterolateral tubercle small, glabrous, shiny. Propleuron with sparse, yellow setae ( Fig. 2 ).

Scutellum: Oval , elongate, almost twice as long as wide, margins recurvate; apex rounded with fine, yellow setae.

Elytra: Length almost three times longer than pronotum. Humeral calli prominent. Elytral margin below humeral calli slightly crenulate with sparse short yellow bristles; sides subparallel, maximum width posterior of the middle. Sutural margin (first elytral costae) tuberculate, glabrous, not distinctly raised and irregularly shaped, longer than wide. Oddnumbered costae (3, 5, 7, and 9) with large, round shiny tubercles, not distinctly raised ( Fig. 3 ). Even-numbered costae (2, 4, 6, 8, and 10 [almost obsolete]) with small, round, irregularly-spaced tubercles; size of even-numbered tubercles approximately the same diameter as intercostal punctures ( Fig. 1 ).

Metathoracic wing: Complete.

Abdomen: five visible sternites (IV–VIII); sternite IV rugose; sternites V–VII with velutinous strip on the distal half ( Fig. 2 ).

Legs: Protibia dorsally keeled, with small apical process present on end of the protibia; surface punctate, apex bidentate. Outer margin with one median tooth and 2–3 smaller basal teeth. Inner margin slightly arched inward with bright yellow setae. Spur pointed forward, as long as the first three tarsomeres combined. Tarsomeres 1–4 equal in length; tarsomere 5 longer than tarsomeres 2–4 combined; claws equal. Apex of mesotibia with pointed apical tooth on outer ventral margin; mesotibia and metatibia slightly arched; outer margin strongly serrate; inner face with long, yellow setae; mesotarsi and metatarsi with tuft of yellow bristles ventrally.

Male genitalia: Symmetrical. Parameres rather simple; internal margin curve near to the base. Median lobe long and symmetrical; dorsal surface shiny and sclerotized. Ventral pieces of median lobe heavily sclerotized; middle of the median lobe with an asymmetrical projection curve backwards on each side. Pars basalis widely membranous dorsally ( Figs. 5–6 ).

Variability (2 females). Length: 7–9 mm, width: 4–5 mm. Both female paratypes have the pronotum and elytra covered by velutinous surface. Antennal clubs pale yellow with golden microsetae. The median longitudinal ridges on the pronotum and anterolateral tubercles are more distinct, broader, and glabrous in both female paratypes. The colour of paratypes is lighter (light grey) than the holotype. No other differences were observed in the external morphology of these specimens.

Distribution and habitat. This species is known only from the Calamuchita Department, in the midwest region of Córdoba, Argentina ( Fig. 20 ). The Calamuchita region is considered an ecotone or transition zone between Chaco and Espinal biomes ( Morrone 2014), composed mainly of xerophytic plants, palm savannas, flood-prone lowlands, and sandy soils ( Oyarzabal et al. 2018).

Etymology. This new species is dedicated to Riccardo Pittino in recognition of his contributions, to date, to the knowledge of Trogidae .

Figures

FIGURE 20. Distribution of Polynoncus pittinoi new species in Argentina.

FIGURE 1–7. Polynoncus pittinoi new species, holotype (MACN): 1, dorsal habitus; 2, ventral habitus; 3, lateral habitus; 4, details of pronotum and head; 5–6, dorsal and lateral views of aedeagus; 7, holotype labels. Scale bar: 1 mm.

FIGURE 8–11. Polynoncus gemmifer (Blanchard, 1847): 8, dorsal habitus; 9, lateral habitus; 10–11, dorsal and lateral views of aedeagus. Scale bar: 1 mm.

FIGURE 12–15. Polynoncus burmeisteri Pittino, 1987: 12, dorsal habitus; 13, lateral habitus; 14–15, dorsal and lateral views of aedeagus. Scale bar: 1 mm.

FIGURE 16–19. Polynoncus neuquen (Vaurie, 1962): 16, dorsal habitus; 17, lateral habitus; 18–19, dorsal and lateral views of aedeagus. Scale bar: 1 mm.