Dichotomius (Dichotomius) quadrilobatus Chamorro, Lopera, & Rossini 2021, new species
Creators: name: Chamorro, William
name: Lopera-Toro, Alejandro
name: Rossini, Michele
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Dichotomius
Dichotomius quadrilobatus

description: Dichotomius (Dichotomius) quadrilobatus Chamorro, Lopera, & Rossini, new species
(Figs. 1 A–F, 5)
Type series. Holotype male (deposited in IAvH), labeled: “ COLOMBIA: META: Piñalito, Finca El Esfuerzo, 200 m (3° 2’ 44" N, 73° 35’ 42" W). 3-iv-1997. Pitfall human excrement. A. Lopera & S. Amezquita ”.
Paratypes. BRAZIL: AMAZONAS: Tabatinga (4°13’40’’S, 69°54’24’’W), ii.1958, Oliveira (2 females, 2 males CMNC). COLOMBIA: AMAZONAS: Buenos Aires, 100 m (3°9’’58.19’’S, 69°58’59.22’’W), iii.1997, C. Durán, human feces baited pitfall (1 male CALT-ECC). Leticia, 215 m (4°11’20’S, 69°56’9’’W), 20–25.ii.1972, Peck & Howden, human feces baited pitfall (2 females, 5 males CMNC). Leticia, 215 m (4°11’20’S, 69°56’9’’W), 23.ii–2.iii.1974, Howden & Nealis (1 male CMNC; 2 males, 1 female BDGC). Los Alpes, Leticia, 213 m (4°4’25’’S, 70°0’5’’W), 23.ii–2.iii.1974, S. Peck, human feces baited pitfall (2 females, 1 male CMNC). Road end, Leticia, 213 m (4°4’9’’S, 69°59’56’’W), 23.ii–2.iii.1974, S. Peck, human feces baited pitfall (2 females CMNC). CAQUETÁ: Florencia, C. Caraño, Vereda Brasil, 365 m (1°39’8’’N, 75°35’37’’W), 3.x.2017, Y. Ramos-Pastrana (15 sex undetermined LEUA). Florencia, Vereda El Limon, Finca El Limon, 644 m (1º22’24.3’’N, 75º36’36.6’’W), 30.ix.2015, Y. Ramos-Pastrana (4 sex undetermined LEUA). Florencia, Vereda La Viciosa. Finca Macagual, 249 m (1°29’55.83’’N, 75°39’25.12’’W), 4.ix.2010, Y. Ramos-Pastrana (3 sex undetermined LEUA). Florencia, Vereda Sabastopol, 348 m (1°29’24.8’’N, 75°24’9.6’’W), 15.v.2015, Y. Ramos-Pastrana (2 sex undetermined LEUA). Montañita, Vereda. Morros, Vereda Las Dalias, 348 m (1°29’24.8’’N, 75°24’9.6’’W), 17.iv.2015, Y. Ramos-Pastrana (28 sex undetermined LEUA). San Vicente del Caguán, Vereda Alto Quebradón, Finca Rancho Veracruz (2°17’55.8’’N, 74°44’29.3’’W), 3.iv.2017, Y. Ramos-Pastrana (1 sex undetermined LEUA). GUAVIARE: San José del Guaviare, Finca Eli, 200 m (2º21’46.2’’N, 72º38’29.9’’W), i.2008, monkey feces, M.C. Santos (3 males, 3 females CALT-ECC). META: Cubarral, Finca El Porvenir, 754 m (3°49’41.85’’N, 73°50’32.78’’W), 30.xi.2017, human feces baited pitfall, A. Lopera & W. Chamorro (1 male, 2 females CALT-ECC). Cubarral, Finca La Cristalina, 661 m (3°49’13.79’’N, 73°50’25.68’’W), 30.xi.2017, human feces baited pitfall, A. Lopera & W. Chamorro (2 males, 2 females CALT-ECC). Cubarral, Finca La Pradera, 576 m (3º49’32’’N, 73º49’16’’W), v.2013, human feces baited pitfall, A. Lopera & D. Martínez (2 females CALT-ECC). Cubarral, Finca La Pradera, 576 m (3º49’32’’N, 73º49’16’’W), 6.xii.2017, A. Lopera & W. Chamorro. (1 male CALT-ECC). Fuente de Oro, Finca Buena Vista, 331 m (3°21’49.85’’N, 73°43’20.89’’W), 25.x.2016, human feces baited pitfall, A. Lopera & W. Chamorro. (1 male CALT-ECC). Fuente de Oro, Finca Buena Vista, 331 m (3°21’49.85’’N, 73°43’20.89’’W), 25.iii.2017, human feces baited pitfall, A. Lopera & W. Chamorro. (1 female CALT-ECC). Fuente de Oro, Finca La Herradura, 296 m (3°17’40.75’N, 73°36’33.17’’W), 17.x.2016, human feces baited pitfall, A. Lopera & W. Chamorro. (1 male CALTECC). Granada, Los Cambulos, 334 m (3°22’55.56’’N, 73°44’34.00’’W). 28.x.2016, human feces baited pitfall, A. Lopera & W. Chamorro (1 female CALT-ECC). Piñalito, Finca El Esfuerzo, 200 m (3°2’44’’N, 73°35’42’’W), 3.iv.1997, human feces baited pitfall (47 males, 46 females CALT-ECC; 2 males ICN). Puerto Gaitán, Estación Rubiales, 214 m (3°44’55.05’’N, 71°27’46.93’’W), ix–x.2015, J.L. Montes (2 males, 2 females CALT-ECC). San Martín, Finca Camaguey, 406 m (3º44’57.51’’N, 73º39’40.61’’W), 4.x.2017, J. Mendevil & C. Quevedo-Vega (1 male CALT-ECC). META: 16 km E Villavicencio (4°7’14’’N, 73°29’30’’W), 2–4.iii.1972. S. Peck, forest, human feces baited pitfall (1 female CMNC). 30 km E Villavicencio (4°4’43’’N, 73°22’23’’W), 1–4.iii.1972, S. & J. Peck, forest, human feces baited pitfall (13 males, 8 females CMNC). 33 km E Villavicencio (4°5’37’’N, 73°21’12’’W), 2–4.iii.1972, human feces baited pitfall, S. & J. Peck. (1 male, 1 female CMNC). PUTUMAYO: Santiago (1°9’N, 77°0’W), i.1980, Bolle (1 male CMNC). VAUPÉS: Caparú, 100 m. 30.ix.1995, human feces baited pitfall, S. Amézquita (1 male CALT-ECC). Río Apaporis, Caparú, Biological Station, 200 m (1º1’S, 69º5’W), 1.ii.1995, B.D. Gill (1 female BDGC). Río Apaporis, Caparú, Biological Station, 200 m (1º1’S, 69º5’W), 27.xi.1995, B.D. Gill (1 male BDGC). ECUADOR: SUCUMBÍOS: Aucayacu, Río Eno, 15 km de Lago Agrio, 291 m (0º3’21’’S, 76º35’33’’W), 25.viii.2007, human feces baited pitfall, D. Buñay (1 female CALT-ECC). Chiritza, Río Aguarico, várzea forest, 265 m (0°5’26.24’’ S, 76°30’39.7’’W), 30.ix.2019, human feces baited pitfall, W. Chamorro (1 male CONRAZ). Comunidad Siona, Río Shushufindi, 260 m, moretal forest (0°12’56.25’’S, 76°32’11.48’’W), 11.x.2019, human feces baited pitfall, W. Chamorro (1 male CALT-ECC). Dureno, Río Aguarico, 150 m (0°2’40’’N, 76°41’50’’W), 23–28-ix.1977, L. Peña (1 female CMNC). Shushufindi, Miss Ecuador, Río Eno, 260 m (0°9’48.68’’S, 76°34’0.71’’W), 9.x.2019, human feces baited pitfall, W. Chamorro (1 male CONRAZ). ORELLANA: Tivacuno, Río Tiputini, Parque Nacional Yasuní, 234 m (0°38’54.05’’S, 76°21’26.37’’W), 15.xi.2020, human feces baited pitfall, P. Araujo. (1 female CONRAZ). PERU: LORETO: Río Pucacuro, Helipuerto HP 12, 200 m (2°9’22.69’’S, 75°42’59.12’’W), 20.iv.2008, human feces baited pitfall, W. Chamorro (1 male CONRAZ).’
Literature records. As “ Dichotomius (Boreus) sp.” (in Sarmiento-Garcés & Amat-García 2014: 44).: COLOMBIA: AMAZONAS: Leticia vía a Tarapacá km 7, 120 m. Leticia vía a Tarapacá km 11, 90 m. CAQUETÁ: Puerto Solano, Parque Nacional Natural Chiribiquete, Río Saramano, 250 m. Chiribiquete, Río Cuñare-Amu, 250 m. GUAVIARE: San José del Guaviare. Reserva Nukak, Santa Marta, 250 m. Nukak, Cerro. Tomachipan, caño Cocuy, Cerro Moyano, 200 m. META: Parque Nacional Natural Tinigua, Río Duda, 350 m. Puerto López El Naranjal, 220 m. NARIÑO: Ipiales, Territorio Kofán, Cuenca alta de los ríos Rumiyaco–Ranchería, 700 m. VAUPÉS: Caparú. Igapó, 100 m. Terraza. R. N. Mosiro-Itajura, Colina, 100 m.
As “ Dichotomius sp.” (in Chamorro et al. 2019b: 9): ECUADOR: PASTAZA: Bosque Protector Oglán Alto, 570 m.
As “ Dichotomius boreus ” (see Ampudia et al. 2020: 61): PERU: LORETO: Reserva Nacional Allpahuayo Mishana, near km 24.6 & km 28.0 on the Iquitos–Nauta road, 145-151 m.
Etymology. The specific epithet quadrilobatus means “with four lobes” and refers to the structures on the pronotum.
Diagnosis. Dichotomius quadrilobatus differs from other species of the D. boreus species group by the following combination of characters: (1) clypeus with symmetrically transverse carina, upper margin of clypeal carina concave medially (Figs. 1 A–B, D), (2) anterior pronotal edge with margin beaded and distinctly widened medially; superior pronotal lobes with anterior edge obtusely acuminate (forked to transversally truncate in D. boreus) and divergent (closer and not divergent in the other members of the D. boreus species group); external apices of the lobes marked and pointing forward. In addition, remarkable differences are found in the morphology of the male genitalia: apex of parameres pincer shaped (normal in D. boreus); dorsal edges of the parameres parallel and close proximally, clearly divergent near the apex, and convergent apically (dorsal edges close throughout and divergent at the apex in D. boreus); lamella copulatrix differs in shape of the left lobe, whose margin of inferior branch of the bifurcation is broadly rounded (clearly acuminate in D. boreus). To date, D. quadrilobatus, is the largest species within the D. boreus species group, with some specimens exceeding 31 mm in length.
Description. Body measurements. Male (Figs. 1A, C–D): length 19–32 mm (holotype 31.2 mm); width 11–19 mm (holotype 18.6 mm). Female (Fig. 1B): length 22.1–27.0 mm in length; width 12.8–17.9 mm. Color. Dorsal side of body black to reddish brown (holotype matt black), antennomeres and mouthparts reddish brown, antennal club dark yellow and dull. Head. (Fig. 1D) Semicircular, wider than long. Clypeal margin feebly sinuate at middle, clypeal surface strongly wrinkled. Clypeal carina high and trapezoidal, located behind clypeal edge. Clypeogenal suture marked, slightly swollen medially. External edge of genae rounded, with small tubercle in proximity of the clypeogenal junction. Frons with trituberculate carina; central tubercle higher than the lateral tubercles, triangular shaped, and with acute apex; lateral tubercles low and wide. Pronotum. Wider than long; anterior pronotal margin beaded, posterior margin wider at the middle, posterior margin of bead obtusely pointed backwards, lateral edges of the pronotum with brown setae. Pronotal surface smooth and bright, with simple, irregular punctures; anterior region declivous. Medial suture deep, dividing the lobes longitudinally forming a “T” with lobes anterior margins (Figs. 1 A–B). Lobes square, outer edges normally with rounded projection at apex. Mediobasal region of pronotum with punctures simple and rounded. Lateral fovea of pronotum located on pronotal anterior ridge that connects superior lobes, ridge above foveae forming carina-like projection. Deeply excavated fovea located between anteromedial and posterolateral edge of pronotum. Thoracic sterna. Proepisternum with small spiniform process between procoxae, procoxae with rounded apex, proepisternal surface heavily punctate anteriorly, punctures ocellate with long setae. Propleural surface pubescent on anterior and lateral regions, glabrous in posterior region. Prosternal surface rough, smooth in the middle, sparsely pubescent, with carina at middle. Mesosternal surface rough, anterior edge feebly rounded, central and posterior regions smooth, anterolateral regions with strong and ocellate punctures associated with long, dense setae. Mesepisternum densely punctate. Metasternal disc finely punctate, with feeble groove at middle. Elytra. Surface smooth, without microsculpture. Striae shallow, more impressed on the elytral disc and apex, striae punctures rounded, separated by at least 1.5 times the size of the puncture. Interstriae feebly convex and with fine punctures. Legs. Profemora, mesofemora, and metafemora completely smooth, with long setae on anterior and posterior edges, Protibial surface smooth dorsally and rugose ventrally, protibial spur acute, directed inwards. Mesotibial and metatibial surface smooth, external edge strongly serrate and internal edge finely serrate, both edges with long setae. Metatibial spur feebly emarginate at apex. Abdomen. Sternites 2–6 without microsculpture and with small, rounded punctures along anterior and posterior edges; posterolateral regions pubescent and with ocellate punctures. Pygidium. Wider than long, surface smooth, with small, dense punctation, margins complete. Male genitalia (Fig. 1E). In dorsal view, parameres narrower apically, sides rather straight and not sinuate, apices rounded and curved inward, assuming the shape of pincers. Dorsal edges of parameres simple, parallel and close proximally and medially, divergent near apex and convergent apically. In lateral view, ventral side of parameres straight, excavated near the phallobase, dorsal side of parameres evenly curved toward apex. Endophallites. Lamella copulatrix (Fig. 1F): horseshoe shaped, with left inferior lobe elongate and developed upward, right lobe distinctly wider, bent upward at the bottom; apex of right lobe bifurcated, superior branch acuminate and directed upward, while inferior branch is widely rounded and directed internally. See Fig. 1F for the remaining endophallic structures.
Intraspecific variation. Males and females of D. quadrilobatus are morphologically very similar, but males can be recognized by the shape of the posterior margin of the anterior pronotal bead, which is pointed backward (it is simply curved in females) (Fig. 1B), clypeal carina is narrower in males (clearly wider in females), and the last abdominal sternite is narrower at middle in males (evenly wide in females). Small specimens (about 21 mm) may lack of clypeal carina and have reduced and somewhat rounded pronotal projections.
Remarks. Sarmiento-Garcés & Amat-García (2009, 2014) provided a short description, along with two illustrations of the head and pronotum of a Dichotomius species, which was considered by the authors themselves to be a close relative of D. boreus. Although apparently aware of describing a new species, the authors did not provide any new name for this Dichotomius, nor selected any name-bearing type specimen to fix the identity of this species, which was initially called “ Dichotomius af. boreus ” (Sarmiento-Garcés & Amat-García (2009) and later “ Dichotomius (Boreus) sp.” (Sarmiento-Garcés & Amat-García (2014). In both papers, the authors included the species in their identification keys, which would lead one to suppose that they considered the series of specimens examined to belong to a distinct species. It is unknown why these authors did not validate a name for this species under the articles of the International Commission on Zoological Nomenclature (1999).
Distribution. This species is distributed in Brazil, Colombia, Ecuador, and Peru and inhabits lowland forests (terrafirme forests), white sand forests (in Peru, locally known as “varillal”), and foothill forests in the Amazon and Orinoco regions (Fig. 5). According to the biogeographical analysis proposed by Morrone (2014), and considering our current knowledge on its distribution, D. quadrilobatus occurs in the biogeographical provinces of Sabana, Napo, and Imeri. This new species has been recorded from 85– 750 m. The record from Santiago, Putumayo Department (1°9’N, 77°0’W), Colombia, which is located at 2000 m, may be erroneous.
Temporal data. Collected all months of the year except June and July.
description: Published as part of Chamorro, William, Lopera-Toro, Alejandro & Rossini, Michele, 2021, A new species and distribution records of Dichotomius Hope, 1838 (Coleoptera Scarabaeidae: Scarabaeinae) in Colombia, pp. 193-206 in Zootaxa 4942 (2) on pages 200-202, DOI: 10.11646/zootaxa.4942.2.3, http://zenodo.org/record/4600445