Genus Coilodes Westwood, 1846

Figs 1–14

Coilodes Westwood, 1846: 163 (original description).

Coilodes – Erichson 1847: 717 (taxonomy). — Lacordaire 1856: 135 (redescription). — Scudder 1882: 73 (catalogue). — Lucas 1920: 195 (catalogue). — Blackwelder 1944: 217 (checklist). — Allsopp 1984: 106 (checklist). — Escobar 1997: 422 (ecology). — Ratcliffe & Ocampo 2001: 352 (taxonomy). — Ocampo 2002: 125 (taxonomy). — Ratcliffe 2002: 7 (checklist). — Ocampo & Ballerio 2006: 191 (checklist). — Ocampo & Hawks 2006: 8 (molecular phylogeny). — Orozco & Pérez 2008: 38 (ecology). — Ocampo 2010: 201 (taxonomy). — Otavo et al. 2013: 741 (ecology). — Rodrigues et al. 2013: 213 (ecology). — Ballerio & Grebennikov 2016: 49 (phylogeny). — Basílio et al. 2023: 5 (phylogeny).

Coelodes – Erichson 1847: 717 (incorrect subsequent spelling: taxonomy). — Lacordaire 1856: 135 (redescription). — Gemminger & Harold 1869: 1075 (catalogue). — Arrow 1912: 37 (catalogue). — Paulian 1938: 230 (key). — Howden & Gill 1987: 2074 (taxonomy). — Feer 2000: 33 (ecology). — Uchoa & Rodrigues 2019: 21 (ecology).

Gnombolbus – Prokofiev 2013a: 1 (original description); Prokofiev 2013b: 1 (synonymy).

Type species

Hybosorus gibbus Perty, 1830 (junior synonym of Coilodes humeralis) by original designation.

Diagnosis

Coilodes is distinguished from other Neotropical Hybosorinae in the body shape being strongly convex, the elytra having sparse twin lines composed of punctures and the mandible being dorsally excavated. In addition, this genus is distinguished from the other Hybosoridae by the presence of sexual dimorphism both in the pronotum (convex in females and excavated in males) and in the tarsal claws (simple in females and with a middle tooth in males).

Etymology

The name “ Coilodes ” is masculine in gender, as it was treated in the original description (Westwood 1846). This term comes from the Greek κοιλότης (koîlotes) derived from κοίλος (koîlos). Although it was stated by Westwood (1846) as “convexitas”, it means concave.

Redescription

Male

MEASUREMENTS. Length 4.4–8.7 mm. Width 2.6–5.1 mm. Body convex, oval and shiny.

HEAD. Surface smooth or strigulate. Frons, in dorsal view, subrectangular; two small tubercles in the middle or one long tubercle formed by the fusion of the small ones; proximal border rounded; lateral margin variable. Canthus strong; distinct area expanded downwards with erect bristles; groove inconspicuous, medially extending up to the lateral margin of the frons. Clypeus subtrapezoidal or subrectangular; lateral margins weakly rounded; apex usually straight; thin and sparse setae throughout the anterior margin dorsally; frontoclypeal suture absent. Labrum semicircular; sparse setae spread along the entire dorsal margin; surface without punctures. Mandibles dorsally excavated, protruding beyond the apex of labrum; lateral margin smooth; setae on the basal half; one tooth at the inferior area of the mandibular apex. Labium with mentum subquadrate or subrectangular; labial palps with four palpomeres; basal palpomere twice as wide as long; second and third palpomeres subglobose; distal palpomere barrel-shaped, length equal to the second and third palpomeres combined. Maxilla subtriangular; long setae throughout surface; maxillary palp with four palpomeres; basal palpomere curved; second and third palpomeres longer than wide; distal palpomere barrel-shaped, length equivalent to the sum of the previous three. Antenna with 10 antennomeres; scape with long and erect setae; antennal club with three antennomeres; club with basal antennomere cupuliform, pubescent distally, sparse, short setae on its base.

PRONOTUM. Convex; excavated medially; usually subtrapezoidal, posterior margin wider than anterior margin or equal in size; medial length usually longer than the anterior and posterior margins; anterior margin with subacute angles; posterior margin rounded and weakly produced medially; lateral margin convex, setae and punctures usually absent.

SCUTELLAR SHIELD. Subtriangular, twice as long as wide; mostly without punctures; apex punctate.

ELYTRA. Double row of longitudinal punctures, sutural stria usually complete; elytral disc glabrous; external margins with short setae; elytral epipleuron complete, wider at the apex; posterior margin of elytra entirely covering tergite 8 (pygidium).

VENTER. Hypomeral surface strigulate, setose; prosternum with midlength elevated, transversally grooved; anterior margin variable in shape, mesoventrite and metaventrite usually smooth.

LEGS. Procoxa conical; surface strigulate. Protrochanter joint with the procoxa rounded, distally angulate. Profemur with posterior margin carinate; surface smooth, with sparse setae. Protibia with inner margin convex; surface with long setae; carinate; single spur; external margin with three larger teeth and series of smaller denticles along the entire margin. Protarsi with tarsal insertion beneath the protibial second tooth. Mesothoracic and metathoracic legs smooth. Mesotrochanter and metatrochanter subtriangular with bifurcated apex. Mesofemur and metafemur carinate on posterior margin. Mesotibia and metatibia with erect setae; apex weakly expanded; pair of spurs with sharp apex, inner spur as long as the protibial spur; outer spur ⅓ longer than the inner one. Tarsi with five tarsomeres, each tarsomere twice as long as wide, distal tarsomere twice as wide as the previous; tarsal claws toothed medially.

ABDOMEN. Six ventrites with recumbent setae.

GENITALIA. Parameres asymmetrical; tegmen with or without a dorsal lobe.

Female

Length 5.1–8.3 mm. Width 3.0– 4.7 mm. As the male except by pronotal excavation absent and tarsal claws simple.

Taxonomic history of Coilodes Westwood, 1846

Mannerheim (1829) described two Hybosorus species: H. humeralis and H. niger in “Decription de quarante nouvelles espèces de Scarabéides du Brésil ”, published in Mémoires de la Société impériale des Naturalistes de Moscou. According to the author, even though the generic attribution was doubtful, he decided to include them in the genus Hybosorus.

Perty (1830) described Hybosorus gibbus, a species from Brazil, but he also questioned its position in this genus. In 1840, Laporte (alias Castelnau) succinctly described four more species of Hybosorus, amongst them H. brasiliensis, this also from Brazil.

The name Coilodes appeared for the first time when Westwood (1846) merged a small group of South American species previously included in Hybosorus. According to this author, these two genera differ from each other, besides in their distribution, by the mandible shape and the presence of sexual dimorphism. The dimorphism involves the excavated pronotum and the tarsal claws with one medial tooth in males, and convex pronotum and simple tarsal claws in females. Westwood (1846) designated Coilodes gibbus as the type species, accompanied by drawings of mouthparts, protibia and the male tarsal claw. He also described three new species: C. parvulus (Brazil), C. castaneus (Colombia) and C. chilensis (Chile). Westwood also synonymized Hybosorus brasiliensis and H. geminatus (the latter is a nomem nudum; this name was cited in Dejean’s catalogues, in 1833 and 1837, but without a description) with C. gibbus. Based on the species distribution, he suggested that many other Hybosorus from Central and South America should be transferred to Coilodes. The seven species transferred to Coilodes were: the two described by Mannerheim (1829), H. humeralis and H. niger (misspelled by Westwood as H. auger); H. rufulus (Castelnau, 1840); and the four cited in Dejean’s catalogues (Dejean 1833, 1837), H. testaceus and three nomina nuda, H. discus, H. granarius, and H. minutus.

Erichson (1847) proposed the name Hybosoridae for the family, based on the number of antennal segments (10) and the presence of strongly fused abdominal segments. This author included six genera: Hybosorus MacLeay, 1819; Phaeochrous Laporte, 1840; Coilodes Westwood, 1845; Chaetodus Westwood, 1845; Dicraeodon Erichson, 1847; and Apalonychus Westwood, 1845, and suggested changes in the names of two genera, Coilodes to ‘ Coelodes ’, and Apalonychus to ‘ Hapalonychus ’. Lacordaire (1856) used the same names proposed by Erichson and redescribed Hybosoridae and its six genera.

MacLeay (1864) described C. bimaculatus in Coelodes [sic], for an Australian species from Port Denison. Despite the discrepant distribution, the author stated doubts about the generic position of this species due to the lack of sexual dimorphism in the pronotum and the tarsal claws, used by Westwood (1846) as diagnostic for the genus.

In the catalogue of Coleoptera by Gemminger & Harold (1869), Coilodes was composed by eight species: C. bimaculatus MacLeay, 1864; C. castaneus Westwood, 1846; C. chilensis Westwood 1846; C. gibbus (Perty, 1830); C. humeralis (Mannerheim, 1829); C. niger (Mannerheim, 1829); C. parvulus Westwood, 1846 and C. rufulus (Castelnau, 1840) (included in Coilodes after suggestion of Westwood 1846). Five years later, Harold (1874) transferred C. bimaculatus to Liparochrus Erichson, 1848. Then, Preudhomme de Borre (1886) transferred C. rufulus to Apalonychus, which was synonymized years later with A. waterhousei by Arrow (1909).

Bates (1887) cited new distribution records for C. castaneus (Nicaragua and Costa Rica) and a small unidentified specimen from Guatemala, but without any further information about it.

Arrow (1903) described three other species of Coilodes (still using the ‘ Coelodes ’ spelling): C. nigripennis (from St. Vincent, Leeward side), C. punctipennis (from Ecuador) and C. fumipennis (from Amazonas, Brazil). In his catalogue of Coleoptera (Arrow 1912) the same author updated the composition of ‘ Coelodes ’ to nine species: C. castaneus; C. chilensis; C. gibbus; C. humeralis; C. niger; C. parvulus; C. fumipennis; C. punctipennis and C. nigripennis.

Lucas (1920) redressed the spelling to “ Coilodes ”. However, Pic (1928) resumed the use of the spelling “ Coelodes ”, which was also reproduced by Paulian (1938). The former also indicated the existence of a variety of C. gibbus (“ Coelodes gibbus v. nov. testaceus ”). Blackwelder (1944) used the original spelling for the genus in his checklist, and included within Coilodes the same nine species cited by Arrow (1912). The author also attributed a feminine grammatical gender to its names (C. gibba, C. parvula). However, the name “ Coilodes ” is masculine in gender in its original description (see also Art. 30.1.4.4 of the ICZN Code; ICZN 1999). Four years later, Robinson (1948) described C. ovalis from Venezuela, based only on female specimens, using once more the generic spelling suggested by Erichson (‘ Coelodes ’).

The first checklist of Hybosoridae was published by Allsopp (1984), where the author ranked the group as a subfamily of Scarabaeidae (Hybosorinae). Supported by the International Code of Zoological Nomenclature (which came into effect in 1958), Allsopp (1984) resumed the original (and current) spelling of Coilodes and listed ten species in the genus: the nine cited by Arrow (1912) and Blackwelder (1944), plus C. ovalis.

In the molecular phylogeny of Hybosoridae by Ocampo & Hawks (2006), Coilodes was found to be more closely related to the Oriental genus Phaeochroops Candèze, 1876 than to Hybosorus or even to Metachaetodus Preudhomme de Borre, 1866, although that was the only other Neotropical genus of Hybosorinae used in the analysis. In their catalogue of Hybosoridae, Ocampo & Ballerio (2006) synonymized C. niger with C. humeralis, differing from Allsopp (1984) only in this synonymy.

Prokofiev (2013a) described Gnombolbus orosi, a new genus and species of Bolboceratinae (Geotrupidae), but in the same year, he synonymized this genus with Coilodes, and the species became a junior synonym of Coilodes castaneus (Prokofiev 2013b).

Finally, in the most recent morphological phyllogeny proposed by Basílio et al. (2023) including all Hybosorinae genera, Coilodes was recovered as the sister group of Frolovius (a monospecific Neotropical genus), but distant of all other Neotropical Hybosorinae genera.

Taxonomic discussion

Coilodes is distinguished from other Central and South American genera within Hybosorinae by the presence of an excavated mandible. This character can be observed in African and Asian genera such as Hybosorus MacLeay, 1819; Phaeochridios Lansberge, 1887; Phaeochroops Candèze, 1876; Phaeochrous Castelnau, 1840 and Seleucosorus Kuijten, 1983. This divergence among the Neotropical genera of the subfamily was recovered in the analysis performed with molecular data by Ocampo & Hawks (2006) that shows Coilodes as more closely related to Phaeochroops than to the Neotropical genus Metachaetodus. In the morphological hypothesis proposed by Basílio et al. (2023), except for the close relationship with Frolovius, the divergence from the other Neotropical genera was also recovered. In that study, Coilodes and Frolovius are considered sister groups, closely related to Seleucosorus and the Palearctic genus Hypseloderus Faimaire, 1893 (Basílio et al. 2023).

Geographical distribution

Coilodes occurs in the Neotropical Region, from Central America (Nicaragua, Costa Rica, Panama and the Antilles) to South America (French Guiana, Venezuela, Colombia, Ecuador, Chile, Peru, Bolivia, Brazil, Paraguay and Argentina). However, the record from Chile is doubtful. No records are yet known from Guyana, Suriname, or Uruguay (Fig. 14).

Biological data

Coilodes usually presents copronecrophagous habits. It is commonly collected using vertebrate faeces or meat in bait traps. Some authors reported the association of adults with carcasses of many kinds of vertebrate, including mammals (monkey, sloth, pig, hedgehog, opossum, rabbit, and mouse), birds (chicken), reptiles (lizard), amphibians (frog), and fishes (Cornaby 1974; Wehncke & Dalling 2005; Young 1983; label data, personal observation). This association mostly occurs in the first stages of decomposition. In addition, specimens were collected in carcasses of invertebrates (ant, shrimp, squid, and earthworm), in fungi, and a few times in decomposing fruit (Young 1983; label data). They are considered good flyers (Lacordaire 1856), with diffuse distribution and diurnal habits (Young 1983). There are records of adult specimens of Coilodes collected using light traps, which suggests attraction to light (label data). They also bury themselves quickly when threatened (personal observation). In addition, stridulating behaviour has been observed in adults of C. humeralis (personal observation).

Identification key to males of Coilodes species

1. Aedeagus with dorsal lobe of tegmen (Fig. 5F, J–K) ........................................................................ 2

– Aedeagus without dorsal lobe of tegmen (Fig. 4F, J–K) ................................................................... 7

2. Aedeagus with the dorsal lobe base in the middle of tegmen (Fig. 5F, J) ......................................... 3

– Aedeagus with the dorsal lobe base on the right side of tegmen (Fig. 12F, J) .................................. 5

3. Clypeus subtrapezoidal in shape with angulate ends (Fig. 5C); lobe of tegmen long, reaching the base of the parameres (Fig. 5F, J–K) ......................................................................................................... 4

– Clypeus subrectangular in shape with rounded ends (Fig. 8C); lobe of tegmen short, less than one half the distance between the base of the lobe and the base of the parameres (Fig. 8F, J– K). Brazil ............................................................................ Coilodes niger (Mannerheim, 1929) stat. rev.

4. Pronotum subelliptical with lateral margins strongly rounded and posterior margin as wide as the anterior one (Fig. 5E); colour ranging from dark brown to black (Fig. 5A). Brazil, Paraguay and Argentina ........................................................................... Coilodes humeralis (Mannerheim, 1929)

– Pronotum subtrapezoidal in shape, with lateral margins straight and posterior margin wider than anterior one (Fig. 3E); yellowish brown in colour (Fig. 3A). Brazil ................................................... ............................................................................. Coilodes edeiltae Basílio & Vaz-de-Mello sp. nov.

5. Lobe of tegmen with apex sharp (Fig. 12J) ....................................................................................... 6

– Lobe of tegmen with apex rounded (Fig. 13J). Brazil and Peru .......................................................... ............................................................................. Coilodes skelleyi Basílio & Vaz-de-Mello sp. nov.

6. Lobe of tegmen long, reaching the base of the parameres (Fig. 12J). Ecuador ................................... .................................................................................. Coilodes ravii Basílio & Vaz-de-Mello sp. nov.

– Lobe of tegmen short, less than one half the distance between the base of the lobe and the base of the parameres (Fig. 1J). Colombia ............................ Coilodes bezerrai Basílio & Vaz-de-Mello sp. nov.

7. Right paramere with distinctly rounded apex (Fig. 4H, J) ................................................................ 8

– Right paramere with straight or almost straight apex (Fig. 6H, J) .................................................. 10

8. Left paramere placed ventrally (Fig. 11G, K).................................................................................... 9

– Left paramere fully located on the left side (Fig. 9G, K). Colombia, Trinidad and Tobago and Venezuela .......................................................................................... Coilodes ovalis Robinson, 1948

9. Tegmen with small, sharp projection next to the base of the right paramere (Fig. 4J). Colombia, French Guiana and Brazil ......................................................................... Coilodes fumipennis Arrow, 1909

– Tegmen without a sharp projection and with a more sclerotized region next to the right paramere base (Fig. 11J). Ecuador, Peru and Bolivia ......................................... Coilodes punctipennis Arrow, 1909

10. Right paramere with at least one of the lateral margins arched (Fig. 6H, J) ....................................11

– Right paramere with both lateral margins straight (Fig. 2H, J). Nicaragua, Costa Rica, Panama, Saint Vincent and the Grenadines, Colombia and Ecuador ............... Coilodes castaneus Westwood, 1846

11. Clypeus subrectangular, wider than long (Fig. 6C); left paramere curved at the apex, with curvature area rounded (Fig. 6I, K). Brazil ...................................................................................................... 12

– Clypeus subtrapezoidal, as wide as long (Fig. 10C); left paramere curved at the apex, with curvature area angulated (Fig. 10I, K). Brazil ............................................ Coilodes parvulus Westwood, 1846

12. Right paramere with transparent region on its distal half (Fig. 6H, J). Brazil ..................................... ................................................................................ Coilodes lunae Basílio & Vaz-de-Mello sp. nov.

– Right paramere without transparent region on its distal half (Fig. 7H, J). Brazil ................................ ............................................................................... Coilodes mayae Basílio & Vaz-de-Mello sp. nov.