Pygodiscodon Wittmer 1966
Creators: name: Biffi, Gabriel
name: Constantin, Robert
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Cantharidae
Pygodiscodon

description: Pygodiscodon Wittmer, 1966
(Figs 1–58)
Pygodiscodon Wittmer, 1966: 411 (original description). DELKESKAMP (1977): 245 (catalogue); BRANCUCCI (1980): 290 (classification); CONSTANTIN (2010a): 40 (key); CONSTANTIN (2010b): 12 (faunistics); CONSTANTIN (2015): 5 (faunistics); CONSTANTIN (2016): 5 (key); CONSTANTIN (2017): 63 (key).
Type species. Pygodiscodon obscurum Wittmer, 1966 by monotypy.
Comparative diagnosis. Males of Pygodiscodon differ from Discodon in the outer claws on the mid- and hind tarsi with a small, fine tooth protruding in an acute angle (in Discodon, the outer claw is apparently split at the apex), and in the last tergite variously shaped, with impressions, constrictions and prominences, and a pair of juxtaposed glandular pores at the apex (in Discodon, the last tergite is usually broad and flat with single posterior glandular pore on either side).
Description. Body length: 5.0–8.8 mm. Head dark brown to black, sometimes light brown behind eyes; frons, clypeus and base of mandibles pale yellow to orange; apex of mandibles and palpi light to dark brown; antennae dark brown to black, sometimes antennomeres yellowish-white; pronotum pale yellow to orange with dark brown to black medial patch; legs light brown to black; thorax, elytra and abdomen dark brown to black. Head, antennae, pronotum, and elytra densely covered with short and thin pubescence. Males: Head, including eyes, nearly as wide as pronotum; frons flat; occipital region convex; clypeus emarginated, slightly prominent medially; mandibles falciform, acute, without accessory teeth. Last maxillary and labial palpomeres securiform. Antennae (Figs 7–12) long, surpassing middle of elytra; antennomeres conical to subserrate, slightly compressed dorso-ventrally, with longitudinal lines. Eyes small and slightly prominent to large and very prominent. Pronotum wider than long; anterior margin slightly to broadly arched; lateral margins slightly emarginated, distinctly notched in basal third. Elytra almost parallel, wider medially, around twice longer than wide. Wings (Fig. 14) ‘Silis type’: radial cell 2R 1 open, vein r incomplete, r-m not coinciding with r, Cu and A not divided, cu-a barely visible. Legs slender; tarsomeres increasing in length from pro- to hind leg; forth tarsomeres with basal transverse split; inner prothoracic tarsal claws (Fig. 15) broadly lobed basally; outer claws on meso- and metathoracic tarsal claws (Fig. 16) with small, fine tooth protruding in acute angle. Abdomen (Figs 17–34) slightly sclerotized; last ventrite bilobed; last tergite variously shaped, with impressions, constrictions and prominences; pair of juxtaposed apical glandular pores. Aedeagus (Figs 41–58): tegmen very short dorsally and long and broad ventrally, completely covering median lobe; parameres slender; median lobe broad and membranous; internal sac partially exposed, bearing spine-like sclerites.
Females: similar to males; eyes slightly smaller and less prominent; antennae shorter, without longitudinal lines; pronotum without lateral notches; tarsal claws simple; abdominal ventrite VII (Figs 35–40) entire, wider than long, lateral margins arched, distal margin with projecting tip; abdominal tergite VIII simple, without distinct impressions, constrictions or prominences.
Etymology. No etymology was given in the original description of Pygodiscodon. The name is derived from Discodon Gorham, 1881, established by this author on the notching in the sides of pronotum of males (disco refers to the centre of pronotum and - odon (m.) is the Greek word for tooth). Therefore, the name Pygodiscodon is a masculine (ICZN 1999, art. 30.1.2), and the mandatory changes in spellings of species names are henceforth made accordingly (ICZN 1999, art. 34.2).
Distribution. Guyana, Suriname, French Guiana, Brazil (Figs 59–60).
Key to species of Pygodiscodon Wittmer, 1966
1 Eyes large, prominent; anterior margin of pronotum broadly rounded, anterior angles indistinct; males: antennae strongly flattened; tergite VIII with a truncate apical border bearing a median, slender projection directed upwards (Figs 23–25). ................................ ........................................................ P. monoceros sp. nov.
– Eyes small, not prominent; pronotum subrectangular, anterior angles rounded; males: antennae slightly flattened; tergite VIII longer, with broader and stronger apical projections. .................................................... 2
2 Antennae entirely black, sometimes with slightly lighter antennomeres X–XI; metathoracic coxae with unciform backwards-pointing projections (Fig. 13); males: straight longitudinal lines on antennomeres VI–XI (Fig. 8); abdominal tergite VIII with a short, broad and truncate projection with glandular pores and a flap-like dorsal projection (Figs 20–22). ... P. gurupi sp. nov.
– Antennae black, except for pale yellow antennomeres XI, or IX and X; regularly shaped metathoracic coxae, without unciform projection; males: longitudinal lines not straight and not present on last two antennomeres; abdominal tergite VIII slender and prominent. ......... 3
3 Antenommere X–XI yellowish white, legs brown; males: longitudinal lines from antennomeres VI–IX (Fig. 12); last abdominal ventrite with lobes long and acute on the apex (Fig. 32); abdominal tergite VIII with a short median projection without dorsal tooth (Figs 32–34). ........................... P. touroulti Constantin, 2010
– Antennomeres IX–X yellowish white, legs mostly light brown to pale yellow; males: longitudinal lines from antennomeres III or IV to VI or VII, not straight, varying in length and width; last abdominal ventrite formed by a pair of lobes with rounded apex; abdominal tergite VIII with a long median projection with a dorsal tooth (Figs 17–19, 26–31). ....................................... 4
4 Males: longitudinal lines from antennomeres III to V (Fig. 11); abdominal tergite VIII (Figs 29–31) with a trapezoidal median projection with a pair of dorsal longitudinal ridges culminating in an acute, upwards- -pointing tooth. .................................. P. similis sp. nov.
– Males: longitudinal lines from antennomeres III or IV to VI or VII; abdominal tergite VIII with a parallel-sided median projection. .................................................. 5
5 Males: abdominal tergite VIII (Figs 26–28) with a slender median projection; dorsal surface with a large, rounded, apical tooth. ......................................... ................................................ P. obscurus Wittmer, 1966
– Males: abdominal tergite VIII (Figs 17–19) with a broader median projection; dorsal surface with a pair of dorsal longitudinal ridges and a central apical tooth. .................................................. P. apicicornis (Pic, 1910)
Natural history and distribution of Pygodiscodon
Specimens of Pygodiscodon are rarely collected or recorded in collections and consequently little is known about the natural history of the species. CONSTANTIN (2010b) reported a large series of P. apicicornis collected with light and interception traps during a one-year inventory in French Guiana, showing an occurrence period from the end of June to beginning of March for males, and from July to November for females. However, specimens collected in Guyana and Suriname increase the period of occurrence of the species within the whole year for males and from May to December for females.
Also, for P. touroulti, the available records show even occurrences of males and females in the interception flight traps during the whole year, with a peak of emergence in January and February. Both P. apicicornis and P. touroulti appear equally widely distributed over French Guiana and are often collected together in the same traps. At Mont Itoupé, they were observed mostly at 600 m altitude, while P. monoceros is established closer to the top, at altitude of 800 m.
Pygodiscodon gurupi sp. nov. was collected with light traps in a patch of Amazonian forest in the transition between the Amazon and Cerrado biomes in the Maranhão State, northeastern Brazil. The majority of specimens of P. monoceros sp. nov. was attracted by an automatic trap combining a Polytrap cross-glass interception device with a white-pink LED light, but two specimens were attracted by a conventional UV light trap. Specimens of P. similis sp. nov. were collected with Malaise traps at Reserva Ducke, a small forest reserve in the vicinity of Manaus, in central Amazon, and by beating vegetation along the edge of a forest clearing at the Iwokrama Research station, Guyana. Pygodiscodon obscurus is still known only from its type locality and its surroundings.
The genus was previously recorded only from French Guiana and Brazil (Pará: Belém). The new records for the six species extend the distribution of Pygodiscodon to Guyana, Suriname and the Brazilian states of Amapá, Amazonas and Maranhão, from the centre to the northern and eastern reaches of the Amazonian forest (Figs 59–60).
description: Published as part of Biffi, Gabriel & Constantin, Robert, 2018, Taxonomic revision of Pygodiscodon (Coleoptera: Cantharidae), pp. 77-90 in Acta Entomologica Musei Nationalis Pragae 58 (1) on pages 78-90, DOI: 10.2478/aemnp-2018-0008, http://zenodo.org/record/3676782