Dichotomius (Selenocopris) globulus ( Felsche, 1901 )

Valois, Marcely C., Silva, Fernando A. B. & Vaz-de-Mello, Fernando Z., 2022, A taxonomic revision of the globulus species group of Dichotomius Hope, 1838 (Coleoptera: Scarabaeidae: Scarabaeinae), Journal of Natural History 56 (1 - 4), pp. 119-147 : 139-142

Dichotomius (Selenocopris) globulus ( Felsche, 1901)

( Figures 2 (s–u), 6))

Pinotus globulus Felsche 1901: 140–141 ; Gillet 1911: 60; Luederwaldt 1929: 676, 678, 751; Blackwelder 1944: 207; Pereira 1947: 318, 319, 1953: 387.

Pinotus fortepunctatus var. catenatus Luederwaldt 1931: 300 ; Blackwelder 1944: 207; Pereira 1947: 318, 322. New subjective synonymy.

Dichotomius globulus: Vulcano and Pereira 1967: 586 ; Howden and Young 1981: 129; Medina et al. 2001: 138; Krajcik 2006: 54; 2012: 91; Sarmiento-Garcés and Amat-García 2014: 97, 98; Vaz-de-Mello and Nunes 2016: 299.

Diagnosis

Currently, D. globulus is exclusively known from the Brazilian and Peruvian Amazon Basin ( Figure 6 ). It is characterised by its distinct oval body shape (( Figure 2 (s)); elytral striae almost as wide as their punctures ( Figure 2 (s)); head covered with ocellate punctures, on anterior region punctures form transverse rows; surface of elytral interstriae completely shagreened in male; ventral surface of metafemora densely covered with coarse punctures at apical two-thirds ( Figure 2 (t)). Paramera approximately rectangular, thin in lateral view, apex rounded and blade shaped. Lower membrane between paramera thinner at posterior third.

Redescription (male)

Body length: 9 mm. Dorsum black, opaque ( Figure 2 (s)). Head: clypeal edge bidentate, teeth rounded, separated by a shallow V-shaped emargination ( Figure 2 (s)). Clypeogenal junction rounded. Surface with different-sized ocellate punctures; punctures forming transverse rows at anterior clypeal region ( Figure 2 (s)). Cephalic process produced into a small central tubercle. Antenal club with light brown tumescence. Thorax: pronotum approximately twice wider than long. Pronotal disc convex, anteromedian region lacking knobs, horns or excavations ( Figure 2 (s)). Surface of pronotal disc with ocellate punctures as dense as on anterior angles. Mid-longitudinal sulcus of pronotum well impressed on posterior half. Whole surface of hypomera covered with ocellate punctures; anterior and lateral regions with punctures bearing short orange setae. Prosternum filled with ocellate punctures. Mesoventrite filled with ocellate punctures, usually bearing short orange setae. Metaventrite surface with ocellate punctures, except on disc; punctures on anterior region usually bearing short setae. Meso-metaventral suture distinct. Mid-longitudinal sulcus of metaventrite feebly marked posteriorly. Lateral lobes of metaventrite with ocellate punctures larger than those on anterior region. Elytra: slightly convex in lateral view. Humeral callus distinct. Striae thin and with well-defined punctures, spaced by twice their diameter. Interstriae I–VII slight convex, barely shiny medially, with shagreened microsculpture; medial region with less distinct microsculpture surrounding smooth dots. Legs: protibial spur curved at apical fifth. Metatibial spur deeply emarginate apically. Ventral surface of profemora densely covered with setiferous ocellate punctures over their entire extension ( Figure 2 (t)). Ventral surface of the mesofemora with ocellate punctures at apical half. Ventral surface of metafemora basally with scattered ocellate punctures which become densely distributed towards the apex. Meso and metafemora bearing a longitudinal groove along their whole extension, wider on apical half. Abdomen: ventrites covered with ocellate punctures laterally, punctures medially distributed in a single row along the anterior edge ( Figure 2 (s)). Pygidium twice wider than long, convex medially. Surface with ocellate punctures spaced by half their diameter. Apex of the pygidium margined. Tegmen: in dorsal view, paramera rectangular. Apex of paramera truncate. In lateral view, apical half slightly narrower than base. Dorsal surface of paramera smooth, lacking longitudinal carina or spine-like projections. Basal portion of paramera in ventral view deeply excavated laterally. Ventral sclerotised membrane between paramera abruptely thinner at posterior one-third. Female: clypeal teeth acute, separated by a deep V-shaped emargination. Sixth ventrite 2 times longer than fifth. Elytral interstriae shagreened, except by a narrow smooth band along medial portion.

Taxonomic remarks

Two main contributions have been published on the taxonomy of the species here assigned to the globulus group. The first was carried out by Luederwaldt (1929), in which the author proposed the ‘ batesi section’ (which includes D. globulus ), but instead of providing a full redescription for the species in that section (including the species treated here, D. globulus ) he only quoted Felsche’s original descriptions, translated into Portuguese. The second contribution was the first revision of the ‘ batesi section’, performed by Pereira (1947). However, like Luederwaldt (1929), Pereira did not examine type specimens of any of the species-group members and only quoted original descriptions ipisis litteris.

Pereira (1953) found four specimens supposedly belonging to D. globulus in the Institut royal des Sciences naturelles, Brussels, Belgium (IRSN). According to the latter author, two specimens have labels from ‘ Perú’ and two specimens have labels from ‘ Pará’ (Pará State, northern Brazil) . Based on those specimens, Pereira (1953) proposed a subjective synonymy between D. globulus and D. fortepunctatus . By reading Felsche’s original description, one can conclude that the original description of the species was based on a single specimen, a male, as the author stated that the clypeal teeth were rounded (females have acute clypeal teeth), and from the exact body length measurement of 11 mm (‘ Länge 11 mill’) . Furthermore, Felsche also mentioned in the original description that the type series comes from ‘ Amazonas’ . We found six specimens of D. globulus in Carl Felsche’s (1839– 1914) collection, which is currently housed in the SMTD. None of those specimens was labelled ‘ Amazonas’; rather, their labels indicated ‘ Iquitos’ ( Peru) and ‘ Manaos’ as collecting localities . ‘ Amazonas’, in early twentieth-century German, meant simply ‘ Amazon rainforest’ . Therefore, Felsche’s citation was not a reference to the Brazilian state of Amazonas . He wrote ‘ Amazonas’ because all the specimens known to him came from the Amazon , both those from Iquitos and those from Manaus .

Chamorro and Marin-Armijos (2019) considered the five specimens of D. globulus from Felsche’s collection to be syntypes and designated the male bearing a ‘Types’ label as the lectotype. The latter authors also regarded D. fortepunctatus as a valid species. After comparing the lectotype of D. globulus with the lectotype of D. fortepunctatus housed in the MZSP, we agreed with Chamorro and Marin-Armijos (2019) that they belong to different species. The two species can be distinguished by body shape, punctation pattern on head and elytra, and the genital characters described here for both species (see the diagnosis of D. globulus above).

The limited material available for D. globulus seems to suggest that this species can occur throughout the Amazon region. As far as we know, it is the only species of the globulus group found in the Brazilian portion of the Amazon Basin, as the remaining species are distributed outside the Amazon, in the north-west part of South America ( Figure 6 ).

Luederwaldt (1931) described D. fortepunctatus catenatus based on a female from ‘Cumbase’ (an alternative name for San Pedro de Cumbasa in Peru). According to Luederwaldt (1929) and Pereira (1947), D. fortepunctatus catenatus is distinguished from D. fortepunctatus by having iridescent and shining reflections on its dorsum. Pereira (1953) synonymised D. fortepunctatus catenatus with D. ocellatopunctatus . However, the holotype of D. fortepunctatus catenatus has the surface of the head and of the pronotum covered with dense, coarse punctures, while in D. ocellatopunctatus the head and pronotum have sparse ocellate punctures (see Vaz-de-Mello and Nunes 2016, fig 2A). Chamorro and Marin-Armijos (2019) considered D. fortepunctatus catenatus a synonym of D. fortepunctatus . On the other hand, in comparison with D. fortepunctatus , the holotype of D. fortepunctatus catenatus lacks the opaque microsculpture on the elytral interstriae, which is diagnostic for D. fortepunctatus . In examining the holotype of D. fortepunctatus catenatus we concluded that it is actually a new subjective synonym of D. globulus , based on its densely punctated head and pronotum, the lateral edges of its elytral interstriae covered with shagreened microsculpture, and ventral surface of metafemora densely covered with coarse punctures on the apical two-thirds ( Figure 2 (t)).

Type material examined

Lectotype of Pinotus globulus ♂ [ SMTD]: ‘Iquitos’ // ‘Coll. C. Felsche/Kanf 20, 1918’ // ‘Staatl. Museum fur/Tierkunde Dresden’ // ‘Typus’ // ‘ globulus /Felsche/k. l. Inifaical’ // ‘ LECTOTYPE ♂ / Pinotus / globulus /Felsche/des. F.Z. Vaz–de–Mello, 2014’. Designated by Chamorro and Marin-Armijos (2019) ( Figure 2 (u)).

Paralectotypes 2♀♀ [ SMTD]: ‘Iquitos’ // ‘Coll. C. Felsche/Kanf 20, 1918’ // ‘Staatl. Museum fur/Tierkunde Dresden’ // ‘ PARALECTOTYPE / Pinotus ♀ / globulus /Felsche/des. F. Z. Vaz–de–Mello, 2014’.

Paralectotypes 2♀♀ [ SMTD]: ‘Manaos’ // ‘Coll. C. Felsche/Kanf 20, 1918’ // ‘Staatl. Museum fur/Tierkunde Dresden’ // ‘ PARALECTOTYPE / Pinotus / globulus ♀ / Felsche/des. F. Z. Vaz–de–Mello, 2014’.

Paralectotype ♀ [ SMTD]: ‘Rio Cachiyacu/Iquitos/Stuart.93’ // ‘Coll. C. Felsche/Kanf 20, 1918’ // ‘Staatl. Museum fur/Tierkunde Dresden’. // ‘ PARALECTOTYPE / Pinotus / globulus ♀ / Felsche/des. F.Z. Vaz–de–Mello, 2014.’

Holotype of Pinotus fortepunctatus catenatus ♀ [ MNHN]:‘ PÊROU /CUMBASE’ // ‘EX MUSEO’ // ‘MUSEUM PARIS/1936/COLL.A. BOUCOMONT’ // ‘le meme de San Jose / Costa Rica/ Coll.Sim’ // ‘ Pinotus ♂ /fortepunctatus/Luederw./ab. catenatus/n. var’. New subjective synonymy.

Figures

Figure 2. Holotypes. Dichotomius danieli, male: (a,b) Dorsal and ventral views; (c) labels; (d–f) tegmen in dorsal, ventral and lateral views; D. favi, male: (g,h) dorsal and ventral views; (i) labels; (j–l) tegmen in dorsal, ventral and lateral views. D. rodrigoi, male: (m,n) dorsal and ventral views; (o) labels; (p–r) tegmen in dorsal, ventral view and lateral views. Lectotype D. globulus, male: (s,t) dorsal and ventral views; (u) labels.

Figure 6. Known distribution of species of the globulus group.