Pselaphacus signatus Guerin-Meneville 1841
Creators: name: Martins, Glauco Luis Do Nascimento
name: Pecci-Maddalena, Italo Salvatore De Castro
name: Lopes-Andrade, Cristiano
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Erotylidae
Pselaphacus
Pselaphacus signatus

description: Pselaphacus signatus Guérin-Méneville, 1841
Figs 1–7, 12.
Pselaphacus signatus Guérin-Méneville 1841: 158 [original description]. Type locality: “ Bolivie ”, type deposited at MNHN [according to Alvarenga, 1994]. Crotch 1873: 142 [distribution]; 1876: 421 [distribution]; Gemminger & Harold 1876: 3688 [distribution]; Gorham 1887: 37 [distribution, interspecific variation]; Kuhnt 1909: 59 [distribution]; 1911: 40 [distribution]; Bruch 1914: 382 [distribution]; Curran 1941: 287 [interspecific variation]; Deelder 1942: 82 [distribution]; Mader 1942: 170 [distribution]; 1951: 206 [key to species]; Blackwelder 1945: 464 [distribution]; Skelley 1998b: 12 [catalog]; Suh et al. 2004: 3 [association with fungi]; Robertson et al. 2004: 3 [family level phylogeny]; Suh et al. 2005: 2 [association with fungi]; Murgas 2006: 74 [distribution]; Rossi & Bergonzo 2008: 1 [association with parasitic fungi]; Yvinec 2010: 3 [distribution]; Drilling et al. 2013: 4 [exocrine glands]; McHugh & Chaboo 2015: 5 [distribution]; Lawrence et al. 2022: 72 [hind wing]. Known geographic distribution: Central America to Argentina.
Pselaphacus signatipennis Lacordaire 1842: 84; Crotch 1873: 142 [distribution] (syn.).
Adult diagnosis. Body elongated, elliptical, glabrous and shiny. Head, pronotum and appendages dark brown to black. Elytra red (in fully pigmented adults) with black spots; elongated scutellar spot (up to about 1/4 of the elytral length), a thin black band runs from this spot along the meso-elytral suture and around the outer elytral edge; each elytron has two circular spots near the humeral region, six discal spots at the elytral median portion disposed in two parallel transversal curves projected anteriorly, an elongated heart-shaped apical spot, and nine longitudinal striae of coarse punctures in the red area; surface between striae with fine dense punctation. Penile flagellum with bifurcated head, forming a deep U-shaped emargination; anterior edges pointed and almost parallel (Figs 2–3).
Adult redescription. Measurements with n = 20, unless otherwise specified. TL 8.93–11.92 (10.92 ± 0.93). Body elongate, elliptical, TL/EW 1.67–1.89 (1.82 ± 0.06); GD/EW 0.47–0.58 (0.56 ± 0,03); glabrous and shiny. Head, pronotum and appendages from black to dark brown; elytra red with black spots. Venter homogeneously black or dark brown in fully pigmented individuals; mouthparts dark brown. Head prognathous, glabrous; punctation dense and fine at the frons, however, coarser and sparser ventrally and in the vertex; frontoclypeal suture barely marked on lateral edges, not visible in the median portion. Clypeus markedly emarginate; contour angulate in males (Fig. 4a) and rounded in females (Fig. 4b); punctation fine; surface with short, fine setae. Antennae brown, setose; club with comparatively shorter and denser vestiture, Proportions between the length of each antennomere and that of the 2 nd antennomere, respectively, from 1 st to 11 th (right antenna; n = 1) as follows: 1.50, 1.00, 2.36, 1.09, 1.18, 1.18, 1.18, 1.18, 1.73, 1.36, 1.82; FL 1.00–1.77 (1.54 ± 0.21), CL 0.85–1.31 (1.15 ± 0.12). Eyes glabrous, coarsely facetted; GW 0.69–0.92 (0.85 ± 0.08). Mouthparts (Fig. 2d–h) mobile labrum, apically more sclerotized, anterior edge setose. Mandibles slightly asymmetrical, robust, with few setae; right mandible with three teeth, the most basal least developed, the median most prominent; left mandible with two teeth and a deep emargination between them; prostheca membranous, pubescent, with high density of setae just below mandibular teeth; right mandible with inner edge of the mola longer than that of the left mandible. Maxilla with subtriangular cardo and elongated stipes. Galea subtriangular, with setose extension towards the sagittal plane, setae covering the apical edge; lacinia less sclerotized than galea, with apical and outer edge setose; basal maxillary palpomere approximately twice the length of the two adjacent ones combined; apical palpomere subtriangular, with elliptical row of setae at apex; labial palps with dilated apical palpomere, strongly sclerotized and covered by scattered setae; mentum with subpentagonal elevate plate. Thorax with subtrapezoidal pronotum, black, glabrous, with dense, fine punctation; punctures separated by about three puncture-widths. Anterior pronotal edge with two shallow emarginations just behind eyes. Lateral pronotal borders convergent anteriorly; lateral carina complete; posterior edge expanded medially. Scutellar shield half as long as wide, subpentagonal, glabrous; punctation, fine; BW 0.54–0.85 (0.69 ± 0.09). Elytra EL 6.85–9.54 (8.76 ± 0.73); reddish with black spots; color pattern and punctation as in diagnosis. Hind wings (Fig. 5) Well developed anterior wing strut (AWS), formed by fusion of ScP and RA, up to the beginning of the radial cell (R), where RA divides into RA1+2 and RA3+4; strong MP1+2 and RP. Cu and MP branch out throughout most of the medial field; anal field delimited by the AA3+4, barely visible AP3+4. Prosternum convex, cup-shaped, with slight median emargination on prosternal process; setae barely visible; procoxal cavities oval, externally closed. Mesoventrite convex, with mesocoxal lines internally arched; setae barely visible. Metaventrite convex; punctation and vestiture scarce; discrimen long, almost reaches the mesoventrite; metacoxal lines present. Metendosternite (Fig. 3g) well developed, rigid, translucent yellow; stalk convex; central sclerotization of anterior process approximately 0.30x as long as central sclerotization of the metendosternal stalk; lamina ear shaped. Legs with oval procoxae, subglobular mesocoxae and transverse metacoxae; femora elongated, especially the metafemora, glabrous, without spines, distal margin with tiny, barely visible setae; tibiae elongated, subtriangular, with setae increasing in size and density from base to apex; pro-, meso- and metatibiae with two spurs at the apex of inner margin; tarsomeres 1–3 densely pubescent beneath. Abdominal ventrites with punctation shallow; punctures separated by 1–2 puncture-widths; setae less evident in articulation between ventrites; coxal lines conspicuous on first ventrite; length of ventrites from first to fifth (on the median longitudinal line, n = 1): 1.69; 1.12; 0.87; 0.89; 1.11. Male terminalia (Fig. 3c–f) with penis elongated, slightly curved; internal sac with well-developed flagellum, with a bifurcated head, forming a deep U-shaped emargination, with anterior edges acute and more or less parallel (Fig. 3e); tegmen strongly sclerotized apically, with conical parameres, glabrous basally and pubescent apically. Female terminalia (Fig. 3a–b) with cylindrical gonostyli, strongly sclerotized, with pubescent apex; gonocoxites slightly more sclerotized apically; spermatheca (Fig. 3a) hazelnut-shaped, capsule strongly sclerotized; bursa copulatrix membranous; tergite and sternite VIII well sclerotized, with pubescent posterior edges; spiculum ventrale well developed. A membranous tube, about 1 mm long when fully extended, connects segment VIII to the posterior structures of the terminalia.
Eggs. (Figs 7a–b) Measurements (n = 5): TL 1.08–1.32 (1.23 ± 0.09). Elongated, elliptical, with nearly parallel sides. Embryo white, visible through the translucent eggshell.
First larval instar. (Fig. 7c) Measurements (n = 5): TL 1.15–1.46 (1.18 ± 0.13); PW 0.31–0.42 (0.38 ± 0.04); CAP 0.15–0.38 (0.23 ± 0.10). White, elongated; head capsule, thoracic tergites and legs light brown. Thoracic tergites with transverse light brown plates. Head prognathous, lightly sclerotized; epicranial suture visible; anterior margin of clypeus with median emargination; anterior surface of head with an impression on each side. Stemmata posterior to each antennal insertion, four latero-dorsal, one latero-ventral. Prothorax visibly wider and longer than meso- and metathorax in dorsal view. Abdomen with dorsal medial region slightly more pigmented than remaining tergum; various setae, usually with a darkish patch on the base. Ninth segment smaller, depressed, with a barely visible pair of urogomphi.
Second larval instar. (Fig. 7d) Measurements (n = 5): TL 3.15–4.31 (4.00 ± 0.52); PW 0.73–0.92 (0.85 ± 0.07); CAP 0.46–0.54 (0.54 ± 0.04). Elongated, almost parallel-sided. Tegument whitish. Head capsule, tarsal claws and urogomphi apex slightly brown. Thoracic tergites with transverse light brown plates. Head hypognathous, moderately sclerotized; setae short, barely visible under stereomicroscope. Abdomen with the dorsal medial portion whitish, bearing thin light brown setae. Ninth segment small, depressed, with a pair of small urogomphi.
Third larval instar. (Fig. 7e) Measurements (n = 5): TL 8.54–9.31 (9.23 ± 0.37); PW 1.31–1.69 (1.62 ± 0.16); CAP 0.62–0.85 (0.69 ± 0.08). Elongated, almost parallel-sided; prothorax slightly wider than the remaining body. Tegument yellowish white. Head capsule, tarsal claws and urogomphi dark brown. Thoracic tergites with transverse light brown plates. Head hypognathous, well sclerotized, with some short setae a bit thicker on dorsum. Ninth segment small, depressed, with a pair of well sclerotized urogomphi.
Fourth larval instar. (Figs 6, 7f) Measurements (n = 5): TL 12.77–14.85 (13.92 ± 0.83); PW 2.23–2.46 (2.38 ± 0.09); CAP 1.00–1.15 (1.08 ± 0.06). Slightly fusiform.Tegument cream-colored; thoracic and abdominal tergites with transverse plates, the latter orange in color and bordered by a thick dark brown outline; the plates interrupted in the medial line, with many small and inconspicuous setiferous tubercles. Head capsule, mandibles and tarsal claws dark brown. Head (Fig. 6a–c) prognathous, strongly sclerotized cephalic capsule with short projections covering most of it, each one bearing a distal seta. Epicranial suture marked by a clear area, forming a V-shaped pattern. Depressed portion present in the anterior region, on each side of the suture, separated medially by protuberance. Coronal suture absent. Stemmata posterior to each antennal insertion, four latero-dorsally and one latero-ventrally. Antennae with three antennomeres; first antennomere transverse; second antennomere elongated with a small membranous sensory cone; third antennomere short and cylindrical, with short distal bristles. Frontoclypeal suture complete; clypeus anterior margin with subtriangular emargination, less sclerotized than frons. Mouthparts protracted; labrum (Fig. 6d) transverse, with median emargination anteriorly; mandibles (Fig. 6e) movable, symmetrical, apex 3-toothed, median tooth more prominent; mola and prostheca membranous, with minute denticles; mala prominent, with thick bristles, cardo transverse; maxillary palpi (Fig. 6g) with 3-palpomeres, apical palpomere longer and narrower than the preceding, stipe elongated; labial palpi (Fig. 6f) with 2-palpomeres, first wider than second; mentum and gula subtrapezoidal, membranous. Thorax with prothorax slightly narrower and longer than meso- or metathorax in dorsal view; meso- and metathoracic plates comparatively wider and shorter than prothoracic plate; pair of large annular-biforous spiracles (Fig. 6i–j) located laterally, between pro- and mesothorax. Legs subcylindrical, with thin and short bristles; coxa wide; trochanter subpentagonal; femur wider and longer than tibia; tarsunguli with well-sclerotized claw. Abdomen with 10 segments, ninth visible from above; a pair of annular-biforous spiracles on the sides of each segment from first to eighth. Ninth segment small, depressed, with dorsal orange-colored plate bordered by thick dark brown outline and a pair of well-developed dark urogomphi (Fig. 6h). Tenth segment tubular and ventral, bilobed apically (Fig. 6h).
Pupae. (Figs 7g) Measurements (n = 3): TL 11.15–12.38 (12.31 ± 0.69); PW 2.77–3.15 (3.15 ± 0.22). Adectic, exarate. Whitish, with many setae of different sizes; with sharp projections along each side of the meso-dorsal line from the thorax to the penultimate abdominal segment. Head hypognathous, not visible in dorsal view. Pronotum subtrapezoidal, about as long as the other thoracic tergal plates combined. Abdomen gradually narrowing towards apex.
Remarks
Type specimens of the majority ofAmerican Erotylidae are housed in four major scientific institutions:MNHN,UMZC, BMNH and MRSN (Skelley 1998b, 2009; Pecci-Maddalena et al. 2023). According to Alvarenga (1994), the type of Pselaphacus signatus is housed in MNHN. Based on images provided by a collaborator (see Acknowledgments), we identified a drawer from the Fleutiaux Collection (MNHN) containing the specimen presumably examined by Alvarenga (Fig. 12c–d). Additionally, coauthor ISCPM photographed a drawer from the Crotch Collection (UMZC) containing another specimen labeled as a “type” of P. signatus (Fig. 12a–b), as confirmed by the data presented by Skelley (1998b). Guérin-Méneville (1841) did not specify whether there were one or more specimens in the type series of P. signatus. Therefore, a lectotype must be designated for this species in future studies.
Life cycle and natural history. Specimens of P. signatus are frequently collected from decomposing logs, associated with the basidiomes of the fungus F. brasiliensis (Fig. 1). Adults are often observed and collected in large numbers during both diurnal or nocturnal active sampling. Clusters of larvae are commonly found, usually accompanied by an adult exhibiting some form of parental care. These adults stay close to the larvae and accompanies them during the consumption of basidiomes. During one of our collecting activities, we found eggs and an adult P. signatus inside a cavity in a log. Despite extensive search efforts, we were only able to locate P. signatus eggs on one occasion. The log fragment containing the eggs was taken to the laboratory to monitor their development. In the laboratory, approximately 60 eggs were transferred to a container and kept on a moistened piece of log. After a day, most of the eggs hatched, and the first instar larvae began feeding on the basidiomes of F. brasiliensis provided, while the parental adult remained nearby. It is important to note that the fact that the eggs hatched after a day does not indicate this as the incubation period, as we had no way to determine when the eggs were laid. The developmental time from the first to the fourth instar took about four days. The prepupal stage lasted approximately fourteen days, and the pupal stage lasted about thirteen days. The entire development, from egg to adult, took about thirty-two days. The parental individuals from our collections were dissected to determine their sex. All of the six dissected individuals were females.
Type material, adults. 1 specimen (UMZC), available by images (Fig. 12b), “ TYPE [blue printed label] \ TYPE. \ signatus. [handwritten?]”; 1 (MNHN), available by images (Fig. 12d), “ Pselaphacus signatus [?], [unreadable], Bolivia [handwritten]”.
Other specimens examined. Adults. 1 specimen (CEMT) “ HONDURAS, Sta. Bar. 13km. SE. El Mochito July 31, 1977 CW&L O'Brien & Marshall \ Pselaphacus signatus Guerin, 1841 [handwritten], M.Alvarenga det. [printed], 1984 [handwritten]\ Coleção M. Alvarenga [printed]”; 1 (CEMT) “BRASIL: Ceará. Ubajara. PN Ubajara, Trilha da Samambaia 3°50'25''S, 40°53'56''W. 850m. 16-20.ii.2013. FIT Vaz-de-Mello & Grossi”; 1 (CEMT) “ BRASIL: Mato Grosso. Tangará da Serra. Faz Sudamata. 14°37'19''S 57°58'04''W 332m Mata semidecidual. FIT 10-17- III-2012. RJ Silva.”; 1 (CEMT) “BRASIL: Mato Grosso. Cuiabá. Boa esperança. X.2010 FZ Vaz-de-Mello.”; 1 (CEMT) “Poconé - MT [printed], 06.xii.1997 Erotylidae [handwritten], Arm. Mal. Acuri [printed]”; 3 (CELC) “BR: MG, Viçosa, Mata da Biologia, 14.ii.2020; G.L.N. Martins leg.”. Voucher numbers: CELC005561, CELC005544, CELC005562; 5 (CELC) “BR: MG, Viçosa, Mata da Biologia; 23.ii.2021; G.L.N. Martins leg.”. Voucher numbers: CELC005548, CELC005550, CELC005585, CELC005651, CELC005704; 1 (CELC) “CELC005560 \ BR: MG, Viçosa, Mata da Biologia; 24.ii.2020; G.L.N. Martins leg.”; 1 (CELC) “CELC005648 \ BR: MG, Viçosa, Mata da Biologia; 27.ii.2021; G.L.N. Martins. ”; 2 (CELC) “BR: MG, Viçosa, Mata da Biologia; 28.x.2020; G.L.N. Martins leg.”. Voucher numbers: CELC005563, CELC005543; 2 (CELC) “BR: MG, Viçosa, Mata da Biologia; 30.ix.2020; G.L.N. Martins leg.”. Voucher numbers: CELC005545, CELC005653; 1 (CELC) “CELC005652 \ BR: MG, Viçosa, Mata da Biologia; x.2020; G.L.N. Martins leg.”; 1 (CELC) “CELC005559 \ BRASIL: MG, Viçosa UFV Mata da Biologia 14.iii.2015 leg. I. Pecci-Maddalena & I. Gonçalves ”; 5 (CELC) “BRASIL: MG, Viçosa UFV Mata da Biologia 19.iii.2015 leg. I. Pecci-Maddalena & I. Gonçalves ”. Voucher numbers: CELC005523, CELC005526, CELC005528, CELC005529, CELC005584; 1 (CELC) “CELC005547 \ BRA, MG, Viçosa, Mata da Biologia 23.ii.2021 ”; 2 (CELC) “Brasil: MG, Viçosa " Mata da Biologia " Início de 2015 Aloquio, S & Almeida, J.P.P. leg.”. Voucher numbers: CELC005524, CELC005525; 1 (CELC) “CELC005504 \ Brasil: MG, Viçosa " Mata do Paraíso, coleta manual noturna" 02.xii.2014: leg. Pecci-Maddalena, I.S.C; Lopes-Andrade, C & Chamorro, J.”; 1 (CELC) “CELC005539 \ Brasil: MG, Viçosa " Mata do Paraíso; Caminho das Águas" 12.xii.2014 leg. Lopes-Andrade, C. et al. ”; 1 (CELC) “CELC005520 \ Brasil: MG, Viçosa " Mata do Paraíso: Coleta Manual diurna" 05.xii.2014 leg. Lopes-Andrade, C. ”; 1 (CELC) “CELC005509 \ BR: MG, Viçosa "Mata do Paraíso"; 16.xii.2016 Pecci-Maddalena, I.S.C. & Lopes-Andrade, C. leg.”; 5 (CELC) “Brasil: MG, Viçosa " Mato do Paraíso: Trilha Principal" 15.xii.2014 Pecci-Maddalena, ISC. leg.”. Voucher numbers: CELC003321, CELC005505, CELC005513, CELC005518, CELC005519; 4 (CELC) “BR: MG, Areado; i.2020; G.L.N. Martins leg.”. Voucher numbers: CELC005538, CELC005650, CELC005534, CELC005540; 6 (CELC) “Brasil: MG, Piau 13.xii.2014 Pecci-Maddalena, I.S.C. leg.”. Voucher numbers: CELC005530, CELC005531, CELC005532, CELC005542, CELC005586, CELC005649; 1 (CELC) “CELC005533 \ Brasil: MG, Piau 25.i.2004 leg. Pecci-Maddalena, I.S.C ”; 1 (CELC) “CELC005527 \ Brasil: MG, Juiz de Fora; 07.xii.2014 leg. Pecci-Maddalena, I.S.C. & Maddalena”. Immatures. 27 specimens (CELC) “CELC005708 \ BRA, MG, Viçosa, Mata da Biologia 23.ii.2021 Martins, GLN”; 4 (CELC) “CELC005709 \ Brasil, MG, Viçosa, Mata da Biologia, Martins, GLN Larvas 1º instar P. signatus; Ovos coletados 23.ii.2021; Larvas sacrificadas 24.ii.2021 [handwritten]”; 3 (CELC) “CELC005710 \ BRA, MG, Viçosa, Mata da Biologia 23.ii.2021 Martins, GLN 1º instar de Pselaphacus signatus Ovos coletados 23.ii.2021; Larvas sacrificadas 25.ii.2021 [handwritten]”; 1 (CELC) “CELC005711 \ Larva de 3º instar P. signatus emergiu dia 27.ii.2021 ovos foram coletados dia 23.ii.2021. Martins GLN Mata da Biologia [handwritten]”; 1 (CELC) “CELC005712 \ Ovos de Pselaphacus coletados na Mata da Biologia (Brasil, MG, Viçosa) dia 23.ii.2021 esta larva de 2º instar emergiu dia 26.ii.2021 Martins, GLN leg. [handwritten]”; 3 (CELC) “CELC005713 \ Larvas Pselaphacus signatus criação Adultos coletados na Mata da Bio Final de setembro Início de Outubro 2020 Possivelmente 3º instar [handwritten]”; 8 (CELC) “CELC005714 \ Larvas Pselaphacus signatus. Mata da Biologia 26.x.2020 Martins, G leg. 8 espécimes 3º instar [handwritten]”; 1 (CELC) “CELC005715 \ BRA, MG, Mata da Biologia (Viçosa-UFV) x.2020 Martins (coleta de larvas) 1 pupa p. signatus [handwritten]”; 1 (CELC) “CELC005716 \ 1 pupa. Emergiu dia 14.iii.2021 Ovos coletados em 23.ii.2021 BRA, MG, Mata da Biologia Martins, GLN leg. [handwritten]”; 5 (CELC) “CELC005717 \ BRA, MG, Mata da Biologia (Viçosa-UFV) x.2020 (coleta de larvas jovens) Martins, GLN [handwritten]”; 1 (CELC) “CELC005718 \ 1 pupa. Emergiu dia 23.x.2020. Larvas coletadas em x.2020 Mata da Biologia, Viçosa, MG, BRASIL Martins GLN [handwritten]”; 1 (CELC) “CELC005719 \ 1 Larva de 4º instar sacrificada dia 29.ii.2021 Ovos foram coletados na Mata da Biologia (Brasil, MG, Viçosa) dia 23.ii.2021 [handwritten]”; 1 (CELC) “CELC005720 \ 1 Larva, sacrificada 03.iii.2021 Ovos coletados 23.ii.2021 BRA, MG, Viçosa Mata da Biologia [handwritten]”; 1 (CELC) “CELC005721 \ 1 Larva de 4º instar emergiu dia 28.ii.2021. Os ovos foram coletados no dia 23.ii.2021 BRA, MG, Viçosa, Mata da Biol. Martins, GLN [handwritten].
description: Published as part of Martins, Glauco Luis Do Nascimento, Pecci-Maddalena, Italo Salvatore De Castro & Lopes-Andrade, Cristiano, 2025, Redescription of adults and first description of immatures for two species of Pselaphacus Percheron, 1835 (Erotylidae: Tritomini) from the Brazilian Atlantic Forest, pp. 255-277 in Zootaxa 5620 (2) on pages 257-266, DOI: 10.11646/zootaxa.5620.2.3, http://zenodo.org/record/15219446