Gromphas amazonica Bates, 1870,

Cupello, Mario & Vaz-De-Mello, Fernando Z., 2013, Taxonomic revision of the South American dung beetle genus Gromphas Brullé, 1837 (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini: Gromphadina), Zootaxa 3722 (4), pp. 439-482: 462-464

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Gromphas amazonica Bates, 1870


4. Gromphas amazonica Bates, 1870 

Figs. 12 –13View FIGURES 11 – 12. 11View FIGURES 13 – 15. 13, 18, 21, 27, 31, 38, 45, 51, 56, 60, 64, 66 Type specimens: Lectotype: here designated, female (handwritten “Ega”, Bates’ handwritten “ Gromphas amazonicus Bates  ”, printed on white paper bordered in black “Ex. Musaeo HWBates, 1892 ”, printed on red paper “ TYPE ”, “ LECTOTYPE ”, “ LECTOTYPE Gromphas amazonica Bates  , Vaz-de-Mello, 2013 ”), MNHN, ex col. Oberthür (examined, Figs. 12View FIGURES 11 – 12. 11 a –b). Paralectotype: 1. female (handwritten “S. Paulo Amaz.”, printed on white paper bordered in black “Ex. Musaeo HWBates, 1892 ”, “ PARALECTOTYPE ”, “ Gromphas amazonica Bates PARALECT  , Vaz-de-Mello, 2013 ”); 2. female (handwritten “Pebas”, printed on white paper bordered in black “Ex. Musaeo HWBates, 1892 ”, “ PARALECTOTYPE ”, “ Gromphas amazonica Bates PARALECT  , Vaz-de-Mello, 2013 ”), MNHN, ex col. Oberthür (examined). Third paralectotype, from “Upper Amazons” (Bates, 1870), not located at MNHN or BMNH.

Type locality: Tefé (former Ega), Amazonas, Brazil (type locality of the lectotype, according Article 76.2 of the Code [International Commission on Zoological Nomenclature 1999]).

Redescription: Color: Dorsum and metasternum usually entirely shiny black, dark blue ( Fig. 13View FIGURES 13 – 15. 13 a), or dark green ( Fig. 13View FIGURES 13 – 15. 13 c), without metallic reflections; some specimens reddish-brown ( Fig. 13View FIGURES 13 – 15. 13 b).

Head: Margin of clypeus with four lobes ( Fig. 27View FIGURES 24 – 28) and folded upwardly, especially two medial lobes. Genae and frons completely granulate, including region adjacent to eyes ( Fig. 27View FIGURES 24 – 28). Cephalic projection a raised carina with emarginate apex in major specimens ( Fig. 31View FIGURES 29 – 33), and only slightly projecting with rounded apex in minor specimens.

Thorax: Pronotum globular; lateral region with dense granulation (Fig. 18), density of granulation decreasing posteromedially; posteromedian region smooth or with strongly effaced granulation ( Fig. 13View FIGURES 13 – 15. 13); posterior fossae usually absent, apparent in very few specimens only as two very shallow and almost imperceptible impressions ( Fig. 43View FIGURES 34 – 48. 34). Posterior margin of pronotum rounded.

Mesosternum with dense pilosity ( Fig. 52View FIGURES 49 – 52). Metasternum with variable density of punctation. Anteromedian angle of metasternum convex and with globose apex ( Fig. 51View FIGURES 49 – 52); area in front of anteromedian angle with evident setae (Figs. 18, 51).

Legs: Protibia narrower in males than in females ( Figs. 21View FIGURES 21 – 23 a –b); in ventral view, longitudinal carina with a row of tubercles in its basal half in males (Figs. 20 d, 23 b) and simple in females ( Fig. 23View FIGURES 21 – 23 a). Protibial spur with apex strongly expanded and curved downward ( Figs. 23View FIGURES 21 – 23, 45View FIGURES 34 – 48. 34). In males, inner apical angle of protibia with a long nonarticulated spur bearing a row of setae on its dorsal surface ( Fig. 21View FIGURES 21 – 23 b, white arrow); in females, inner apical angle only with a tuft of short setae ( Fig. 21View FIGURES 21 – 23 a). Apex of apical protarsomere with a long spiniform projection ( Fig. 45View FIGURES 34 – 48. 34). Mesotarsi and metatarsi very broad and with apical tarsomeres only slightly curved apically ( Fig. 48View FIGURES 34 – 48. 34). Metatibiae very broad and robust ( Fig. 41View FIGURES 34 – 48. 34). Metatibial spur with apex distinctly curved ( Fig. 39View FIGURES 34 – 48. 34).

Elytra: Striae very fine and, especially striae 1–4, distinctly carinulate from base to apical slope of elytra ( Fig. 38View FIGURES 34 – 48. 34). Sutural margin glossy and punctate; in some specimens basal third or basal half of sutural margin with sheen and punctation extending laterally into first or second interstria (easily seen in Fig. 15View FIGURES 13 – 15. 13 b).

Abdomen: Pygidium flat, not margined basally ( Fig. 36View FIGURES 34 – 48. 34). Groove of propygidium extending to base of pygidium. Abdominal sternites smooth or sparsely punctate.

Aedeagus: Phallobase, in ventral view, with a very broad apical membranous area ( Fig. 56View FIGURES 53 – 56 c). Medial sclerite only slightly curved, almost flat, with a narrow and spiniform projection at one end ( Fig. 60View FIGURES 57 – 62).

Measurements: Males (18 specimens): TL: AV: 15.59; MX: 18.1; MN: 13.6; SD: 1.32. PL: AV: 13.73; MX: 15.3; MN: 13.6; SD: 1.32. PW: AV: 9.38; MX: 10.4; MN: 7.7; SD: 0.72. Females (20 specimens): TL: AV: 14.72; MX: 17; MN: 12; SD: 1.32. PL: AV: 12.93; MX: 14.4; MN: 10.5; SD: 1.12. PW: AV: 8.86; MX: 10.1; MN: 7; SD: 0.83. Total (38 specimens): TL: AV: 15.13; SD: 1.38. PL: AV: 13.31; SD: 1.09. PW: AV: 9.11; SD: 0.82.

Intraspecific variation and taxonomic discussion: Gromphas amazonica  shows a wide variation in the punctation of the sutural margin of elytra and metasternum; some specimens show conspicuous punctation, while in others it is only slight. Variation is also seen in the spiniform projection of the female protarsus; most specimens have it well developed and evident ( Fig. 45View FIGURES 34 – 48. 34), while some others seem to have the projections worn and consequently shortened.

Posterior pronotal fossae are usually absent in G. amazonica  , but occasionally they are represented by a pair of small, almost imperceptible, punctiform pits ( Fig. 43View FIGURES 34 – 48. 34). We observed these fossae only in two specimens; a small male from Itacoatiara (Amazonas, Brazil) and a large female from Afuá (Pará, Brazil) ( Fig. 13View FIGURES 13 – 15. 13 c). Although the other specimens did not show any trace of these fossae, it is clear that this is no more than individual variation, the same occurring in G. inermis  , also a species typically without posterior pronotal fossae (see more on the discussion of G. inermis  ).

Although the non-articulated spur of the male protibiae is unique to G.amazonica  ( Fig. 21View FIGURES 21 – 23 b), its homology with the small tubercle found in the male protibiae of the other species of Gromphas  ( Fig. 23View FIGURES 21 – 23 b, white arrow) is likely (the tubercle, as the non-articulated spur, is absent in females). However, in no other species is this tubercle developed more than an almost imperceptible; in G. amazonica  , the non-articulated spur is visible to the naked eye even in smaller specimens. Other unique characters of G. amazonica  are (a) the elytral striae carinulate beyond midpoint of elytra ( Fig. 38View FIGURES 34 – 48. 34); (b) apical protarsomere with a long spiniform projection ( Fig. 45View FIGURES 34 – 48. 34); (c) mesotarsi and metatarsi very wide; (d) usual absence of metallic reflections; and (e) medial sclerite of internal sac with a spiniform projection ( Fig. 60View FIGURES 57 – 62). The phallobase with membranous apical area expanded in ventral view and the medial sclerite only slightly curved are characters shared in some way with G. dichroa  and G. inermis  , respectively, although in G. amazonica  both characters are much more pronounced.

With G. aeruginosa  and G. lemoinei  , G. amazonica  shares the elytral striae carinulate (in G. lemoinei  and G. aeruginosa  the carinulae are always absent in the apical half of elytra [ Fig. 37View FIGURES 34 – 48. 34], while in G. amazonica  the carinulae reach the apical slope of elytra [ Fig. 38View FIGURES 34 – 48. 34]). Gromphas amazonica  shares only with G. inermis  the margin of the clypeus with four lobes ( Fig. 27View FIGURES 24 – 28) and folded upward; the cephalic projection emarginate apically ( Figs. 27View FIGURES 24 – 28, 31View FIGURES 29 – 33); and the usual absence of posterior pronotal fossae (and their occasional presence in some specimens [ Fig. 43View FIGURES 34 – 48. 34]). (See comparison with G. dichroa  in the discussion of that species).

We examined a single female of G. amazonica  that bears the unexpected locality of Cáceres (Mato Grosso, Brazil) in the Alto Pantanal region, about 1,000 km south of Contamana, Peru, the second southernmost point known for this species. This specimen has distinctly carinulate elytral striae and apical protarsomere with a long spiniform projection, but, unlike other G. amazonica  , it has a strong green color with metallic reflections covering the entire body, especially the head and pronotum. With only one specimen known, it is impossible to say whether this condition is typical of this population of G. amazonica  or just an individual variation (or even that this is the result of mislabeling). If indeed the existence of this Patanal population is confirmed, it would be a case analogous to, for example, Sulcophanaeus faunus (Fabricius, 1775)  , a species widely distributed throughout Amazon Basin with small isolated populations in Paraguay and western São Paulo state (Edmonds 2000).

Comments: Bates (1870) based his description of G. amazonica  on four specimens (“ I do not find any sexual difference in the four specimens I posses ”). Nonetheless, we were able to locate only three of the syntypes at the MNHN, all females; one of them (that from Tefé, former Ega) was designated by us as the lectotype of G. amazonica  .

Bionomics: Figueroa et al. (2012) were the first to publish data on the natural history of G. amazonica  . They report that this species is collected in pitfall traps baited with human feces in forests habitats and, in one case, several specimens were collected in a secondary forest associated with mandioca cultivation ( Manihot esculenta Crantz  ). The specimens that we examined from Afuá, Pará, were also collected on human feces (Paulo R. Magno, MNRJ, personal communication). The specimens examined in this study were collected in July, August, September, November, January, February, and March.

Geographic distribution: Amazonian subregion: Amapa, Varzea, Ucayali, Madeira, and Pantanal. COLOMBIA: Amazonas: Letícia. BRAZIL: Amapá: Macapá. Amazonas: Benjamin Constant, Carauari, Eirunepé, Itacoatiara, São Paulo de Olivença, Tefé. Pará: Afuá ( Ilha do Pará), Porto de Moz (Tapara). Mato Grosso: Cáceres. PERU: Loreto: Mariscal Ramón Castilla (Pebas), Maynas (Iquitos); Ucayali (Contamana; Padre Márquez). San Martin: San Martin (El Porvenir). Ucayali: Coronel Portillo (Callería: Pucallpa; Yarinacocha). ( Fig. 66View FIGURE 66).

Material examined: 22 males and 26 females. BRAZIL: AMAPÁ: Macapá, BR 156 km. 14, 26.XI. 1981, I. S. Gorayeb & Equipe cols.— 2 females (CEMT). AMAZONAS: Benjamin Constant, IX. 1953, I. C. Lima col.— 1 male (MNRJ); Carauari, 57 º 28 ’05”S 05º 40 ’ 75 ”W, 85 m, 19.VII. 2009, L. Nichols, R. Braga & G. Schiffler cols.— 1 male and 1 female (CEMT); Eirunepé (former João Pessoa), Rio Juruá, 10.IX. 1936, Zellibor-Hauff col.— 2 males and 1 female (MNRJ), 1 male and 1 female (FIOC) and 1 female (MZSP); Eirunepé, Rio Juruá, IX. 1936, without collector— 1 male (MZSP); Itacoatiara, without date, Mann & Baker cols.— 1 male (BMNH); Tefé, VIII. 1991, O. Roppa & P. Magno cols.— 2 females (MNRJ). MATO GROSSO: Cáceres, 10.X. 2008, E. Silva col.— 1 females (CEMT). PARÁ: Afuá, Ilha do Pará, Igarapé Juntinta, XI. 1995, P. Magno & C. Júlio cols.— 10 males and 13 females (MNRJ); Porto de Moz, Tapara, I. 1923, J. F. Zikán col.— 1 male (FIOC); Porto de Moz, Tapara, II. 1923, J. F. Zikán col.— 1 female (CEMT). COLOMBIA: AMAZONAS: Letícia, 700 ft., 23.II-02.III. 1974, without collector— 1 male (CMNC); Letícia, 700 ft., Isla Sta. Sophia, 23.II-02.III. 1974, J. Peck col.— 1 female (CMNC); Parque Nacional Natural Amacayacu, 90 m, 23.IX. 1993, collector illegible— 1 female (CMNC). PERU: Ucayali, Coronel Portillo, Yarinacocha, 150m, 08- 15.VII. 2001, D. Curoe col.— 3 males and 1 female (CEMT).