Sylvicanthon enkerlini ( Martínez et al., 1964 ) Cupello & Vaz-De, 2018

Cupello, Mario & Vaz-De, Fernando Z., 2018, A monographic revision of the Neotropical dung beetle genus Sylvicanthon Halffter & Martínez, 1977 (Coleoptera: Scarabaeidae: Scarabaeinae: Deltochilini), including a reappraisal of the taxonomic history of ‘ Canthon sensu lato’, European Journal of Taxonomy 467, pp. 1-205 : 60-65

Sylvicanthon enkerlini ( Martínez et al., 1964) comb. nov.

Figs 6A , 9 B–D, 10B, 11A, 15A, 17A, 20–22

Glaphyrocanthon (Glaphyrocanthon) enkerlini Martínez et al., 1964: 5 , 8, 13, 17–21, figs 1–2.

Canthon (Francmonrosia) enkerlini – Halffter & Martínez 1977: 86.

Canthon enkerlini – Krajcik 2012: 63.

Sylvicanthon sp. – Lima et al. 2013: 91–93.

Etymology

Eponym after the Mexican entomologist Dieter Enkerlin Schallenmüller (1926 – 1995) ( Martínez et al. 1964).

Material examined

Holotype

BRAZIL: ♂, Maranhão, São Luís (“ BRASIL / Eº Maranhao / São Luiz / Coll. Martínez / Sep. 955”, “ HOLOTYPUS ”, “ Glaphyrocanthon / enkerlini / ♂ / sp. nov. / M. H. y H. / A. Martínez det 19 63 ”, “ FICHADO ”, “MACN-En / 1050”), genital capsule removed and glued in a triangular label (MACN-En / 1050) ( Fig. 21 C ).

Additinal material (47 ♂♂, 44 ♀♀)

BRAZIL: Bahia: 1 ♀, Barreiras, Oct. 1991, light trap, without collector ( CEMT); 1 ♀, Barreiras, Nov. 1991, without collector ( CEMT); 2 ♂♂, 1 ♀, Barreiras, Jan. 2003, P. Schmidt leg. ( CEMT); 2 ♀♀, Pilão Arcado, Barra do Brejo, 10º06.677′ S, 42º53.678′ W, 416 m, 5 Dec. 2005, P. P. Lopes leg. ( CEMT); 2 ♀♀, Pilão Arcado, Barra do Brejo, 10º06.677′ S, 42º53,678′ W, 416 m, 27 Mar. 2006, V. Mendes leg. ( MZFS). – Maranhão: 2 ♂♂, 4 ♀♀, Mirador, Parque Estadual do Mirador, Povoado Pindaíba (Mel), 06º41′06″ S, 45º00′26″ W, 1– 5 Jun. 2010, pitfall with human faeces, F. Limeira-de-Oliveira, M. M. Abreu and J. S. Pinto leg. ( CEMT). – Minas Gerais: 1 ♀, Bandeira (“ R. Bandeira ”), Jan. 1932, José Blaser leg. ( MZSP); 1 ♂, Jaíba, Mocambinho, 15º09′03.1″ S, 43º56′03.4″ W, 450 m, 28 Mar. 2012, pitfall with human faeces, A. Fialho leg. ( CEMT); 1 ♀, Três Marias, 17 Mar. 1992, without collector ( CEMT). – Piauí: 1 ♂ (dissected), 2 ♀♀, Canto do Buriti, 18– 22 Nov. 1991, C. R. F. Brandão leg. ( MZSP); 2 ♂♂, 1 ♀, Canto do Buriti, 42º48′05″ W, 08º11′12″ S, 254 m, 5 Apr. 2008, trap with dung, Gillett leg. ( CEMT); 1 ♂, Corrente (“ 10 km N Corrente”), Fazenda Maracujá, 23– 27 Nov. 1991, E. M. Cancello and M. T. Ponte leg. ( MZSP); 1 ♂, Corrente (“ 10 km N Corrente”), Fazenda Maracujá, 23– 27 Nov. 1991, S. T. P. Amarante and C. F. Martins leg. ( MZSP); 1 ♂, Floriano, Fazenda Buriti Sol, 5– 12 Oct. 1991, S. T. P. Amarante leg. ( MZSP); 6 ♂♂, 3 ♀♀, Oeiras (“ 5 km E Oeiras”), Fazenda Talhada, 13– 17 Nov. 1991, C. R. F. Brandão and P. Moutinho leg. ( MZSP); 5 ♂♂, 1 ♀, Oeiras (“ 5 km E Oeiras”), Fazenda Talhada, 13– 17 Nov. 1991, E. M. Cancello and M. T. Ponte leg. ( MZSP); 1 ♀, Oeiras (“ 5 km E Oeiras”), Fazenda Talhada, 13– 17 Nov. 1991, S. T. P. Amarente leg. ( MZSP); 1 ♀, Piripiri, Parque Nacional de Sete Cidades, 04º05′51″ S, 41º42′30″ W, 170 m, 7– 12 Feb. 2013, pitfall with human faeces, Vaz-de-Mello and Grossi leg. ( CEMT); 1 ♂, 4 ♀♀, same collecting data as for preceding but 180 m ( CEMT); 9 ♂♂ (1 dissected), 9 ♀♀, Piripiri, Parque Nacional de Sete Cidades, 04º05′54″ S, 41º42′31″ W, 170 m, 13 Feb. 2013, flight interception trap, Vaz-de-Mello and Grossi leg. ( CEMT); 9 ♂♂, 4 ♀♀, Piripiri, Parque Nacional de Sete Cidades, 04º05′38″ S, 41º42′35″ W, 200 m, 13 Feb. 2013, pitfall with human faeces, Vaz-de-Mello and Grossi leg. ( CEMT); 1 ♀, Piripiri, Parque Nacional de Sete Cidades, 04º06′38″ S, 41º44′48″ W, 180 m, 12 Feb. 2013, flight interception trap, Vaz-de-Mello and Grossi leg. ( CEMT); 1 ♀, Piripiri, Parque Nacional de Sete Cidades, 04º05′03″ S, 41º42′34″ W, 190 m, 7– 12 Feb. 2013, pitfall with human faeces, Vaz-de-Mello and Grossi leg. ( CEMT); 1 ♂, Ribeiro Gonçalves, Estação Ecológica Uruçuí-Una, 08º52′ S, 44º57′ W, 19– 29 Jan. 2001, G. G. Montingelli leg. ( MZSP); 4 ♂♂, 1 ♀, São Raimundo Nonato, Parque Nacional da Serra da Capivara, Jan. 1999, C. A. Matrangolo leg. ( CEMT); 2 ♀♀, São Raimundo Nonato, Parque Nacional da Serra da Capivara, Zabelê, 12 Apr. 2001, A. C. A. Moura leg. ( CEMT); 2 ♂♂, Teresina, Jan. 1953, Oliveira leg. ( CMNC).

Redescription

COLOURATION. Dorsum, metaventrite and pygidium entirely black, without metallic reflections; external edge of clypeus occasionally dark brown. Ventral face of legs ranging from black to dark brown; dorsal face of protibiae reddish-brown.

HEAD. Tegument with diffuse shine and strong alveolar microsculpture, which is usually more marked on frons and genae than on clypeus, which can present diffuse microsculpture; micropunctation always evident throughout dorsal surface, more impressed in areas with sparser microsculpture. Clypeus with four large, acute teeth well separated from one another ( Fig. 6A ; in worn specimens, teeth obtuse); external edge (including teeth) clearly folded up; with a single row of setae covering the base of the four teeth. Genae with strong tooth immediately behind clypeal-genal juncture. Posterior edge of head with a fine margin between eyes; occasionally, margin lacking only at the area adjacent to eyes.

THORAX. Pronotum with shiny and lustrous tegument; alveolar microsculpture usually restricted to sides, where it is very dense; centre with strong micropunctation and without microsculpture, or with very diffuse microsculpture. Posterior edge with fine transverse line at centre (usually extending up to the second elytral stria). Hypomeral cavity with tegument densely covered by long yellowish setae and with depressed area close to external margin, the latter with a weak tubercle; posterior part of hypomeron with long, individual setae (around five) aligned longitudinally close to its external edge ( Fig. 9D ). Metepisternum with posterior region, at the suture with metaventrite, with an evident tubercle ( Fig. 9C ). Metaventrite entirely glabrous; tegument with strong rivose microsculpture at lateral and anterior regions; at centre, alveolar microsculpture very fine and diffuse, slightly more delimited at posterior region; micropunctation very fine, but distinct at centre.

LEGS. Profemora with tegument with strong alveolar microsculpture at anterior region, and alveolar microsculpture at posterior region; without micropunctation; anterior margin, at apex of profemur, interrupted by row of denticles ( Fig. 9B ). Protibiae wide and with internal margin strongly expanded at their apical half ( Fig. 11A ); in its apical half, external margin with three large, acute teeth widely separated from one another, the apical two of subequal length and longer than the basal. Mesofemora margined anteriorly only at their basal two-thirds; unmargined portion with a row of very short setae; tegument with strong alveolar microsculpture at anterior region and gradually with more diffuse microsculpture towards posterior and basal regions, where micropunctation is strong. Metafemora margined only anteriorly, posterior margin absent; tegument with strong rivose microsculpture at apical and anterior regions, with microsculpture gradually more diffuse towards posterior region and base; micropunctation present throughout the tegument, more marked in areas of diffuse microsculpture, especially at base, where it can be very dense. Metatarsomeres II and V subequal in length and longer than the others; metatarsomere IV shorter than the others; the entire meso- and metatarsi with a single continuous row of setae throughout its internal margin.

ELYTRA. With nine very narrow visible striae; in general, first six to seven striae well marked, but never carinulate; from them, striae progressively more effaced and interrupted; humeral carina absent. Tegument of interstriae at centre of elytral disc lustrous and without microsculpture (or with very diffuse microsculpture); lateral and apical regions with strong alveolar microsculpture and diffuse shine; micropunctation present throughout tegument, but more distinguishable in areas without microsculpture. ABDOMEN. Ventrite VI with diffuse rivose microsculpture at middle and more clearly marked on the sides; micropunctation absent or very subtle; both sexes without lateral foveae. Pygidium with tegument with diffuse shine and covered by strong alveolar or rivose microsculpture; in some specimens, microsculpture weaker or even absent at apex; micropunctation obliterated by microsculpture and usually indistinct.

AEDEAGUS. Parameres almost as long as phallobase and symmetrical, both faces flat. In lateral view, parameres simple, without any ventral keel or notch ( Fig. 17A ).

SEXUAL DIMORPHISM. Males: Protibial spur narrow and bifid at apex, with spiniform projections, the external project longer than the internal one ( Fig. 15A ). Ventrite VI strongly narrowed at middle; anterior margin covered only slightly by weak medial expansion of posterior edge of ventrite V. Pygidium very long (length between 1.2 and 0.9 mm). Females: Protibial spur spiniform, simple, and distinctly bent towards external side. Ventrite VI very wide at middle; anterior margin covered by medial flange of posterior edge of ventrite V. Pygidium shorter (between 1.0 and 0.7 mm).

Measurements

Males (N = 14). TL: AV: 6.6 ± 0.64; MX: 8; MN: 5.8. EW: AV: 4.6 ± 0.38; MX: 5,5; MN: 4.1. PL: ME: 2.1 ± 0.2; MX: 2.5; MN: 1.8. PW: AV: 4.0 ± 0.35; MX: 4.8; MN: 3.5. PgL: AV: 1.0 ± 0.09; MX: 1.2; MN: 0.9. PgW: AV: 1.7 ± 0.23; MX: 2.2; MN: 1.3.

Females (N = 15). TL: AV: 6.4 ± 0.58; MX: 7.3; MN: 5.7. EW: AV: 4.5 ± 0.39; MX: 5.2; MN: 3.9. PL: AV: 2.0 ± 0.18; MX: 2.3; MN: 1.7. PW: AV: 3.8 ± 0.31; MX: 4.4; MN: 3.3. PgL: AV: 0.9 ± 0.08; MX: 1; MN: 0.7. PgW: AV: 1.7 ± 0.11; MX: 1.9; MN: 1.5.

Geographical distribution

Dry forests between Cerrado, Caatinga, Amazonia and the Atlantic Forest in the Brazilian north- and southeast.

Ecoregions

Maranhão Babaçu Forests, Cerrado, Caatinga, Bahia Interior Forests.

Collecting sites ( Fig. 22 )

BRAZIL. Maranhão: São Luís, Mirador (Parque Estadual do Mirador). Piauí: Canto do Buriti, Corrente, Floriano, Oeiras, Parnaíba, Piripiri (Parque Nacional de Sete Cidades), Ribeiro Gonçalves (Estação Ecológica de Uruçuí-Una), São Raimundo Nonato (Parque Nacional da Serra da Capivara), Teresina. Ceará: Caucaia. Bahia: Barreiras, Pilão Arcado. Minas Gerais: Bandeira, Jaíba, Três Marias.

Intraspecific variation and taxonomic discussion

If, on the one side, S. enkerlini comb. nov. seems to be the most isolated species in the genus and with no close relationships to any known Deltochilini , on the other side, the studied populations form a cohesive entity without any noticeable geographical variation. In the same way, little intrapopulational variation was observed. The exceptions are the specimens (two males and one female) collected in 2003 by P. Schmidt in Barreiras (Bahia): the alveolar microsculpture of the entire tegument is much stronger on them than on the other individuals, being evident even at the centre of the pronotum (where it is diffuse in the other specimens). The two females collected at the same place in 1991, on the other hand, have microsculpture typical of the rest of the distribution of S. enkerlini , as well as the four females collected between 2005 and 2006 in the municipality of Pilão Arcado, distant only about 300 km from Barreiras. The reason for that difference is unknown to us.

Natural history

Martínez et al. (1964) described S. enkerlini based solely on the male holotype collected in a humid forest surrounding a water reservoir in the outskirts of the city of São Luís, Maranhão, Brazil (“ el ejemplar holotipo y único [...] fue capturado en las afueras de la ciudad de Sao Luiz, dentro del bosque tropical y húmedo que rodea la reserva de agua potable de esa población ”). As they were aware of only this single geographical record, those authors considered S. enkerlini as being a typical Amazonian species. Nonetheless, over the past 25 years, several collections in transitional regions between the Cerrado, Caatinga and Amazonia, in the Brazilian states of Piauí, Bahia, Ceará and Minas Gerais, have revealed the presence of S. enkerlini in that vast area, whereas other collections in regions farther west in the Amazon forest, such as in the state of Pará, have not yielded the species. Therefore, it seems that S. enkerlini is actually an inhabitant of open and dry lowland forests typical of the transitional zone between those three biomes, including the Mata dos Cocais, in the transitional zone between the Amazon rainforest and the Caatinga, where the babaçu palm ( Attalea speciosa Mart. ) predominates. One specimen was collected in 1932 in the municipality of Bandeira, Minas Gerais, an area originally covered by the Atlantic rainforest (ecoregion of Bahia Interior Forests). However, due to the intense anthropogenic activity across this entire ecoregion converting the former humid forest into open areas for agriculture and pasture, it was given the right conditions for the immigration of a fauna typical of Cerrado into that region, S. enkerlini included.

Based on the specimen labels, it is possible to know that S. enkerlini occurs in altitudes between 170 and 416 m and is collected between October and June (no records for May) using pitfall traps baited with human faeces as well as flight interception traps and light traps. The only record of flight activity time is that of Martínez et al. (1964), who said the holotype was collected during the first hours of the evening.

Figures

Fig. 6. Head, dorsal view. A. Sylvicanthon enkerlini (Martínez et al., 1964) comb. nov. B. S. candezei (Harold, 1869). C. S. genieri sp. nov. D. S. proseni (Martínez, 1949) stat. et comb. nov. E. S. seag sp. nov. F. S. securus (Schmidt, 1920) comb. nov. G. S. furvus (Schmidt, 1920).

Fig. 9. A. Sylvicanthon bridarollii (Martínez, 1949), profemur. Note that, as occurs in the other species of the candezei group, there is no denticulation on the anterior edge, which is, by contrast, completely smooth. B. S. enkerlini (Martínez et al., 1964) comb. nov., profemur.Arrow indicates the denticulation of anterior edge, a condition present in both sexes and unique in the genus. C. S. enkerlini, metepisternum. Arrow indicates the small tubercle at the suture between metepisternum and the lateral region of metaventrite. D. S. enkerlini, hypomeron. Notice the row of long setae present on the lateral of posterior region, a condition seen uniquely in this species in Sylvicanthon.

Fig. 21. Sylvicanthon enkerlini (Martínez et al., 1964) comb. nov. A. Dorsal view. B. Ventral view. C. Holotype and its labels.

Fig. 11. Morphological diversity in the protibiae of Sylvicanthon Halffter & Martínez, 1977. A. S. enkerlini (Martínez et al., 1964) comb. nov. B. S. aequinoctialis (Harold, 1869) comb. nov. C. S. securus (Schmidt, 1920) comb. nov. D. S. obscurus (Schmidt, 1920). E. S. furvus (Schmidt, 1920). F. S. bridarollii (Martínez, 1949) (southern populations). G. S. bridarollii (northern populations). H. S. attenboroughi sp. nov. I. S. edmondsi sp. nov. J. S. candezei (Harold, 1869). Note the variation related to the presence and degree of development of an expansion on the internal edge of protibiae and to the number, size and position of the external teeth.

Fig. 17. Aedeagus morphological diversity in Sylvicanthon. A. S. enkerlini (Martínez et al., 1964) comb. nov. B. S. foveiventris (Schmidt, 1920). C. S. candezei (Harold, 1869) (arrows points to the ventral notch). D. S. genieri sp. nov. (idem). E. S. aequinoctialis (Harold, 1868). F. S. proseni (Martínez, 1949) stat. et comb. nov.

Fig. 15. Morphological variation and sexual dimorphism in the protibial spur of Sylvicanthon. A. S. enkerlini (Martínez et al., 1964) comb. nov., ♂. B. S. foveiventris (Schmidt, 1920), ♂. C. S. candezei (Harold, 1869), ♂. D. S. genieri sp. nov., ♂. E. S. aequinoctialis (Harold, 1868), ♂. F. S. aequinoctialis comb. nov., ♀. G. S. proseni (Martínez, 1949) stat. et comb. nov., ♂. H. S. proseni stat. et comb. nov., ♀. I. S. bridarollii (Martínez, 1949), ♂. J. S. seag sp. nov., ♂. K. S. edmondsi sp. nov.,♂. L. S. attenboroughi sp. nov., ♂. M. S. obscurus (Schmidt, 1920), ♂. N. S. furvus (Schmidt, 1920), ♂. O. S. securus (Schmidt, 1920) comb. nov., ♂.

Fig. 22. Distribution of Sylvicanthon enkerlini (Martínez et al., 1964) comb. nov. Note that the species occupies transition zones between the Amazonia, Cerrado, Caatinga and Atlantic Forest biomes, regions much dryer and more open than the humid forests occupied by the species of the candezei group.