Pselaphacus procerus Kuhnt 1910
Creators: name: Casari, Sônia A.
name: Silva, Thiago J.
name: Polizei, Thiago T. S.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Erotylidae
Pselaphacus
Pselaphacus procerus

description: Pselaphacus procerus Kuhnt, 1910
Figs 1–12
Pselaphacus procerus Kuhnt, 1910: 226; 1911: 40; Bruch, 1914: 382; Blackwelder, 1945: 464; Alvarenga, 1994: 7.
Adult diagnosis. Pronotum marginate laterally by a narrow black band; anterior margin with irregular black band, projected at middle forming a triangular narrow band almost reaching mid-length; two rounded black patches on anterior third; posterior margin with irregular black band, projected at middle forming a wide short band with one shorter triangular projection on each side. Scutellar shield black. Elytron with black marks as follow: base marginated by a narrow black band; a band on scutellar region, reaching 5th stria, length about ⅕ of elytron length, with irregular posterior margin; an irregular band on middle, reaching 4th stria, length approximately the same as scutellar band; a longitudinal stripe between 5th and 6th striae, at the same level as middle band; a longitudinal stripe on the elytral suture, reaching the 1st stria between scutellar and middle bands and reaching the 2nd stria after middle band, slightly narrowing toward apex; an oblong stripe near apex, between 3th and 7th striae, slightly oblique, length approximately the same as previous marks; external margin entirely bordered, thicker on the first half. Epipleura black. Ventral coloration almost totally black, abdominal ventrites II-IV laterally brownish-orange, and V almost entirely brownish-orange.
Adult redescription (Figs 2–5) Length: 10.5–13.4 mm (n = 11). Body broad, elongated, wide, parallel-sided. Glabrous and shiny, except the anterior edge of prosternum, ventrally with a row of yellow setae, and tibiae and tarsi with yellow setae. General coloration black, with pronotum and elytra brownish-orange with black marks; labrum, reddish-brown and apices of palpi and labium, brownish. Punctuation fine, weak, and dense; frons with punctuation fine and heterogeneous, thicker at base; gena ventrally with punctuation irregular and thicker; pronotum with punctuation heterogeneous, denser laterally on anterior third, and thicker near middle.
Head (Fig. 2A–D) glabrous; frontoclypeal suture weak with lateral margins convergent posteriorly, interrupted at middle. Frons (Fig. 3A) narrow and marginate laterally on basal half; prominent behind antennal insertions and on eyes, forming canthus, and then gradually narrowed apically, anterior margin not carinate; clypeus anteriorly strongly emarginate at middle forming two well-developed rounded lobes; ocular striae and subocular pores present. Subgenal braces well developed with pores present. Antennae (Fig. 2A–C) not reaching base of pronotum, with 11 antennomeres: 1 st slightly elongate, wide, almost cylindrical; 2 nd short, globular; 3 rd longer, almost as long as 4 th and 5 th together, narrowed at base; 4 th –8 th slightly increasing in width and decreasing in length; three last forming a club. Eyes glabrous, coarsely granulate. Labrum (Fig. 2C) transverse, trapezoidal, wider at middle; swelling transversely near base; distal margin arched; setae of varied sizes, more concentrated near angles and shorter near middle. Epipharynx (Fig. 3B) transverse with one row of wide and short setae near each fore angle, and several campaniform sensilla below; a stout long seta at middle, marginate anteriorly by campaniform sensilla; fine and dense setae inwardly directed surrounded laterally and posteriorly median seta. Mandibles (Fig. 3C–D) symmetrical, elongated, strongly curved with two apical and one wide rounded subapical dorsal teeth; with a brush of setae at base; prostheca elongate, fleshy, formed by short setae; long setae between prostheca and mola; mola with lateral short setae, more concentrated dorsally; mesal area microspined internally dorsal and ventrally. Maxilla (Fig. 3E): cardo transverse with an elongate basal condylar projection and with one pore opening at middle; basistipes and mediostipes elongate and triangular; basistipes with one long seta; galea and lacinia (Fig. 3F–G) separated; galea narrowed at base, rounded externally; lacinia elongate with narrowed apex; galea and lacinia covered by stout long setae, more concentrate near apex. Maxillary palpi with four palpomeres: basal one elongate and curved; second and third short, wider than long; distal wide, securiform, 1.8x wider than long. Labium (Fig. 3E) short and wide; ligula subtrapezoidal, emarginate anteriorly, marginate by short setae; with four pair of setae and many campaniform sensilla near middle (distal and basal shorter); prementum band-like; mentum almost as wide as long with lateral margins sinuous; with a pentagonal elevated plate at middle of anterior third area; basal ⅔ widely concave; concavity rounded anteriorly, including four long setae and about four pairs of short setae. Labial papi with three palpomeres; palpiger band-like with crescent sclerotized area; basal elongate, gradually widened to apex; median transverse and wide, with lateral margin curved and four setae; apical elongate, slightly securiform (slightly longer than wide).
Thorax. Pronotum (Fig. 2A, C–E) wider than long (1.5x wider than long), slightly convex; slightly narrowed at fore angles; lateral margins almost straight, with narrow flap; stronger convex at middle inside lateral weak grooves; fore angles prominent; posterior margin prominent on median third, forming three rounded weak lobes. Marginal pores opening on posterior third and at posterior and anterior angles. Scutellar shield short (Fig. 2A, D), triangular, wider than long; fore angles rounded; glabrous with a few punctures. Elytra (Fig. 2A, E) elongate, 1.55x longer than wide, slightly wider than the basal margin of pronotum; lateral margins parallel on anterior half and slightly and roundly narrowed apically; apices conjointly and widely rounded; moderately convex, lateral margins marginated; nine striae marked by row of coarse punctures; interstices flat and almost same width. Prosternum (Fig. 2B, E) wide; prosternal process gradually expanded apically, with lateral carinae and bilobed apex; two pore openings, one on each side near margin of the prosternal process; procoxal lines straight, not surpassing coxae. Mesoventrite small, slightly convex, anterior edge sinuate, mesocoxal lines curved. Metaventrite convex, glabrous, punctures fine and sparse; metacoxal lines conspicuous; discrimen 0.71x as long as metaventrite. Legs (Fig. 2B, E): procoxae oval; mesocoxae almost globular; metacoxae transverse. Femora wide, smooth, without spines or other outgrowths, slightly constricted subapically, making ventral angles rounded. Tibiae flat, widened apically, internal margin and apex somewhat setose, setae more concentrated on protibiae; two apical spurs. Tarsomeres 1–3 widened and densely setose beneath, tarsal claws simple.
Abdomen (Fig. 2B, E). Ventrites I–V transverse; I–II longer; III–V almost same length; apical narrower, with distal margin widely curved; ventrites with punctuation fine and irregular, coarser laterally, bearing tiny setae.
Male (Fig. 4): Tergite IX (Fig. 4B) narrow, narrower than the width of tergum; gradually slightly narrowed apicad; distal margin widely rounded, marginated by fringe of long setae. Sternite IX (Fig. 4A) elongate, subrectangular at base; apical region roundly narrowed apicad; apex trilobed; lateral lobes widened, extending dorsally and reaching tergite IX; with many long setae, more concentrate laterally; median lobe narrow, shorter than lateral, with distal margin strongly rounded and densely covered the setae. Aedeagus (Fig. 4C–G): penis (median lobe) elongate, curved, with apex narrow; median strut longer than penis, with widened apex; flagellum (virga) longer than penis with head dilated. Parameres short, with many short setae; tegmen slightly expanded basad; tegmen arm short and bilobed.
Female (Fig. 5): Tergite VIII (Fig. 5B) wider than long, slightly narrowed at apex; distal margin almost straight; marginated lateral and anteriorly by band of setae. Sternite VIII (Fig. 5A) transverse with lateral margins slightly rounded; basal prolongation 4.4x sternite length. Bursa elongate, membranous, with microspines. Coxites (Fig. 5D) elongate and setose, surrounded by a ring formed by tergite and sternite IX; each coxite with one segmented stylus with several setae at apex. Spermatheca (Fig. 5C) large and oval; spermathecal ducts sclerotized.
Material examined. BRAZIL. Amazonas: Benjamin Constant, II.940; ex-Coll J. Guérinn16383; Pselaphacus / psecilosomus Lac., J. Guérin. det. 1944 (1 specimen MZSP56285). Mato Grosso do Sul: Três Lagoas, Horto Barra da Moeda, Três Lagoas Agroflorestal / 21.XII.1993, Flechtmann col., Ethanol trap in Eucaliptus grandis stand (1 specimen MZSP56282). Minas Gerais. Uberlândia, Rancho Talismã Ana Gabriela. Rio Aguari / 25.XI.2018. Thiago Polizei & Alice Sparvoli leg. (1♂, 4♀ MZSP 49098 -49102). São Paulo: Piracicaba, XI.1961, R. Reichardt col. (1 specimen MZSP56283). Salto Grande, 8.V.2000, Santos-Silva col. (1 specimen MZSP56284). Marilia, II.945; ex-Coll. J. Guérin 17413; Pselaphacus psecilosomus Lac., J. Guérin. det. 1945 (2 specimens MZSP 56286-56287). Castilho, marg. esq. r. Paraná, X. 1964 Exp. Depto Zool. (2 specimens MZSP 56288-56289).
Variation. The coloration is variable among the eleven examined specimens. All specimens are black with pronotum and elytra brownish-orange with black marks. On the pronotum the median basal black area is narrowed apically, reaching or not anterior margin. Sometimes the longitudinal prolongation is interrupted forming a black area starting at anterior margin. On the elytra, the sizes of black marks are variable. Variation in size was observed in specimens from different localities. Uberlândia specimens (n=5) total body length 10.4–11.0 mm; pronotum length 2.20–2.35 mm, greatest width 4.0– 4.1 mm and elytra length 7.75– 7.65 mm. Marília specimens (n=2) total body length 12.0– 12.20 mm; pronotum length 2.55–2.6 mm, greatest width 4.75–4.8 mm and elytra length 9.1–9.2 mm Castilho specimens (n=2) total body length 11.8–11.90 mm; pronotum length 2.8 mm, greatest width 4.8–4.9 mm and elytra length 8–8.2 mm. In Benjamin Constant specimen (n=1) total body length 12.6 mm; pronotum length 2.7 mm, greatest width 4.85 mm and elytra length 9.4 mm; Três Lagoas specimen (n=1) total body length 13.4 mm; pronotum length 3 mm, greatest width 5.1 mm and elytra length 9.6 mm; Piracicaba specimen (n=1) total body length 10.5 mm; pronotum length 2.35 mm, greatest width 4.35 mm and elytra length 8.1 mm; and Salto Grande specimen (n=1) total body length 10.1 mm; pronotum length 2.25 mm, greatest width 4 mm and elytra length 7.55 mm.
Larvae. According to Wegrzynowicz (2002) the Erotylidae larva undergoes three molts before pupation. The specimens we studied were probably in the last and penultimate instars. The description was based on the last instar larva (mature), and when there were differences in the structures of mature larva with those in the specimens from the early instar, the structure is described in both instars.
Besides the different sizes, the larval instars are easily recognized by the dorsal sclerotized plates on abdomen (Fig. 6A–C) present only in last larval instar and missing (Fig. 10A–C) in the earlier larvae.
Larval diagnosis. Body elongate, more or less parallel-sided, slightly narrowed anteriorly and at apex, subcylindrical, flattened ventrally. General coloration cream with dorsal transverse brown elliptical plates, yellow at middle and with some yellowish shadow outside; head yellowish, darker on early instar; area of stemmata darker, black in older instar; legs partially yellowish or yellowish-brown. Dorsally, pubescence short; setae inserted in darker punctures or tiny tubercles; ventrally apparently glabrous, with sparse tiny setae more concentrated near middle. Dorsally all segments with transverse, elliptical brown plates, yellow at middle; setae short inserted in darker punctures, densely distributed on darker contour and more concentrate laterally; plate of pronotum longer; plates on meso-and metanotum almost same size; plates on tergites I–VI almost same length; plates I–III slightly increasing in width; plates IV–VI slightly decreasing in width; plates VII–VIII slightly longer than previous, VII wider than VIII; plate IX larger, covering almost whole tergite and including urogomphi; urogomphi setose, brown, yellow dorsally. Early instar larvae with transverse sclerotized brown plates only on thorax and a small on first abdominal tergite; plate of pronotum longer; plates on meso- and metanotum almost same size; each plate of thorax, marginated by irregular band of short setae, inserted in darker punctures, and some sparse setae distributed by whole surface; setae on abdominal segments, short, inserted in darker punctures and concentrate transversal median on segments, same place of future plates; urogomphi setose, brown, clear dorsally.
Larval description. (Figs 6–11). Mature larvae: length: 10–18 mm. Early larvae: length: 5–8 mm.
Head (Figs 1A–B, 7A–B, 9A, C–D, 10A–B, 11A–B) protracted and moderately declined, almost globular. Epicranial sutures (Fig. 7A) U-Shaped; coronal suture absent. Frons (Fig. 7A) with two rounded slightly concave areas, and with four pair of setae. Each epicranial half with seven setae inserted in small tubercles; five stemmata below each antenna and three setae near them. Ventrally (Fig. 7B), each side with four setae; two below antennae, each inserted in a small tubercle. In early instar, epicranial suture (Fig. 11A) indistinct; dorsal area with two rounded slightly concave areas near middle, 14 pair of setae of varied sizes, not inserted in tiny tubercle; five stemmata below each antenna and three setae near them and one below; a group of about five short setae near each posterior angle; ventrally (Fig. 7B), each side with seven setae. Antennae (Fig. 7A–E) short, with three antennomeres; antennifer wider, membranous and microspined; antennomere one transverse with two sensilla, and microspined at apex; antennomere two elongate, narrower than previous, at apex with antennomere three and four setae, and two ventral membranous sensoria, one very smaller; antennomere three elongate, reduced with two short setae at apex, and one dorsal campaniform sensillum near apex; apex with some small sensoria. In early instar (Fig. 11C–D), basal antennomere transverse, dorsally with two campaniform sensilla and microspines near apex and ventrally with microspines laterally near apex; antennomere two elongate, dorsally with one campaniform sensillum and one short seta near apex, and ventrally with three short setae near apex, and at apex, with antennomere three and membranous apical sensorium; distal antennomere ventrally with one campaniform sensillum near apex, and three wide and long and three wide and short setae at apex. Frontoclypeal suture (Fig. 7A) present. Clypeus transverse with anterior margin emarginate and posterior prominent at middle; each side with two setae and two campaniform sensilla. In early instar (Fig. 11E), with one seta on each fore angle and each side with two setae near base and one campaniform sensillum. Labrum band-like with anterior margin emarginate; two short setae. In early instar also with four campaniform sensilla. Epipharynx (Fig. 7G) marginate anteriorly by row of short and stout setae midwardly directed, interrupted at middle; median anterior area with group of setae backwardly directed, with a group of about four sensilla each side; subapical area verrucose on each side and setae backwardly directed at middle. In early instar (Fig. 11F), the anterior margin of epipharynx emarginate; each side marginate anteriorly by row of long and thin setae medially directed, interrupted at the middle; the subapical area laterally verrucose; groups of short setae near middle. Mandibles (Fig. 7H–I) symmetrical, slightly longer than wide, wider at basal half; apex blackish in mature larvae; apex concave and tridentate; without accessory ventral process; mola absent; molar area with membranous lobe armed with asperites; one lateroexternal seta. In early instar, mandibles (Fig. 11G–I) were almost as wide as long. Ventral mouthparts (Fig. 9I) retracted. Maxilla (Fig. 7B, J–K). Cardo subtriangular with one seta; stipes elongate, ventrally with six setae (one basal shorter); dorsally with one or two campaniform sensilla, microspined at base galea and lacinia; galea and lacinia fused; mala (Fig. 7J, L–M) bilobed; internal lobe smaller, with rounded apex; ventrally with one seta (with irregular apex in early instar) and one campaniform sensillum; dorsally with teeth, smaller, sharpened and in larger number in early instar, and rounded in mature; external lobe wider with apex almost straight; apex ventrally with small teeth of varied sizes, and dorsally with 5 stout setae; some setae in earlier instar with bifurcate apex. Palpi trimerous: basal palpomere transverse, ventrally with two campaniform sensilla and dorsally with one lateroexternal seta; second transverse, ventrally with one campaniform sensillum and one lateroventral seta; distal elongate, ventrally with one laterointernal seta, and dorsally with one wide lateroexternal seta inserted in groove, and one simple seta, and some small peg-like sensilla at apex. In early instar, maxilla (Fig. 11B, J–K) with cardo transverse, subtriangular with one seta; stipes with six setae and three campaniform sensilla; apex of mala (Fig. 11L–M) almost truncate with weak rounded lobe internally; ventrally with two teeth and six wide setae (three with irregular apex); dorsally with many small and irregular teeth. Palpomere basal transverse, ventrally with two campaniform sensilla; second transverse, ventrally with one campaniform sensillum and one laterointernal short seta; distal, ventrally with laterointernal short seta, dorsally with one seta in groove, and many apical peg-like sensilla at apex. Labium (Figs 7B, O; 11B, N): prementum transverse, ventrally with one long seta below each palp and two short setae and one campaniform sensillum on each side; postmentum elongate, rectangular with two pair of setae and one pair of campaniform sensilla; ligula indistinct. Labial palpi with two palpomeres; basal transverse with one lateroexternal seta; distal elongate with one dorsal campaniform sensillum and peg-like sensilla at apex. Hypopharynx (Fig. 7N) raised in a median rounded area with setae on each side, inwardly directed; median anterior region with four short setae and one longer on each side. Hypopharyngeal scleroma slightly elongated with base curved. Hypostomal rods absent. Ventral epicranial ridges and gula absent. Each segment of thorax, dorsally with sclerotized, transverse, oval-shaped plate, margined by brown and yellow at middle; brown band with dense setae, inserted in small tubercles. In early instar the plates are weakly sclerotized or lacking, and setae are longer and without tubercles at base.
Thorax (Fig. 8A–B, 9B, G) Prothorax (Fig. 6A–C) longer and narrower than mesothorax, shorter ventrally; dorsally convex with large sclerotized plate; plate ventrally glabrous; prosternum with one anterior sclerite on each side; episternum with two small flattened lobes near each coxa, each with one clear sclerite and one short setae; anterior larger. Ventrally with two small plates on each side, clearer or only one each side on early instar. Meso and metathorax of almost same size, each with one short elliptical sclerotized plate with setae; mesothorax anterolaterally with one anullar-biforous spiracle (Fig. 8G) on each side, marginated by a crescent sclerotized patch and a lateroposterior brown patch on each side; meso and metacoxae marginate externally by two tubercles on each side, anterior yellowish and posterior brown. In early instar (Fig. 10A–C), metathorax laterally sometimes bearing two brown patches. Legs (Figs 6B–C, 8C–D) long, increasing in size from anterior to posterior ones; coxa inserted distant from midline of thorax; coxae robust, sclerotized with short setae inserted in sclerotized punctures; setae more concentrate internally; trochanter with setae more concentrate ventrally; trochanter and femur darker, elongated, and setose; pretarsus wide, with two basal setae. In early instar (Figs 8E–F; 10B–C; 12G–H), legs similar to mature, apparently setae a little longer. Legs clearer and more setose in early instar.
Abdomen (Fig.6A–C), segments I–III slightly increasing in length and width; segments IV–VIII increasing in length and decreasing in width; segments I–VIII, each with a dorsal elliptical plate, brown and yellow at middle, with setae inserted in small sclerotized tubercles, irregularly distributed; dorsal plates slightly decreasing in width and increasing in length to apex direction; each segment with one laterodorsal annular-biforous spiracle (Fig. 9F), smaller than thoracic ones and one pleural rounded lobe on each side, with several tiny setae; segment IX (Fig. 9J– L) narrower, gradually narrowed apicad, with dorsal plate almost covering whole tergite and fused with urogomphi; each side with one vestigial spiracle. Urogomphi (Fig. 9J–L) fix and strongly sclerotized, with several flattened tubercles with one seta at base. Segment X (Fig. 9J, L) ventral and tubular, apicoventral, apex forming two lobes. In early instar (Figs 8H–I; 10A–C; 12K), dorsal plates are absent or small and present only on first or first and second segments; urogomphi (Fig. 12K), sclerotized only at the apex, and setae of the abdomen are anchor-shaped.
Material examined. Brazil. Minas Gerais: Uberlândia, Rio Araguari, Rancho Talismã Ana Gabriela, 25.XI.2018, T. Polizei & A. Sparvoli, (ca. 300 early and 36 mature larvae) (MZSP 10375).
Habitat. The adults associated with the immatures were collected in the summer of 2018 in fruiting bodies of Favolus Fries. (Polyporaceae). The specimens were found by the last author (TTSP) forming gregarious balls over the fruiting of fungi in a rotten wood trunk, in a ranch nearby Aguari river, Uberlândia municipality, Minas Gerais state, Brazil. The hundreds of larvae were feeding on fungus and taken care by five adults (one male and four females). This kind of behaviour has been reported in the Erotylidae family, especially in Pselaphacus, where another seven species have exhibited maternal care of the brood mass (Chaboo & McHugh, 2010).
Distribution. Brazil (first country record): Amazonas (?), Minas Gerais, Mato Grosso do Sul and São Paulo States. Argentina: Misiones (Fig.1). The original description of P. procerus was based on material from Argentina. During the study of Erotylidae collection of MZSP, it was found one specimen from Amazonas state, Brazil. After the comparison of this specimen with the original description and remainder specimens, there is no doubt that the specimen from Amazonas state (Amazon region) also corresponds to P. proceru s. However, the material of this region, including this specimen, is very old and came from a private collection (J. Guérin), incorporated at the MZSP a few years ago. Based on the distribution of the other specimens of this species, collected in Central and Southeast Brazil, and the type locality in Argentina (Fig. 1), this specimen from Amazonas may be mislabeled.
Comparative notes. Based on adults, P. procerus is similar both in size and coloration to other two species of the genus: P. poecilosomus Lacordaire, 1942 and P. vitticollis Crotch, 1973. It can be distinguished from these two by the absence of a black mark at the humeral angle of the elytron and by the separation of the longitudinal strips from the sutural marks.
Comparing the larvae of Pselaphacus procerus with that of P. nigropunctatus it was verified that the larvae of both species are different, especially in coloration. In the first species, there is darker dorsal plates, yellow with contour dark-brown, and in second, the plates are brownish, but in both the setae are inserted in small sclerotized tubercles. Both species present epicranial suture U-shaped, antennae with three antennomeres, antennomere 2 with membranous sensorium, mandibles concave with apex 3-toothed, prostheca membranous, lobate and microspined, and urogomphi fixed and one-segmented.
In a more detailed comparison of larvae of both species, it was verified that Pselaphus procerus (P.nigropunctatus) has clypeus and labrum separated (partially fused); gular sutures absent (gular sutures short); some marginal areas of mandibular teeth micro-toothed (straight); urogomphi with a distal tooth (without tooth).
description: Published as part of Casari, Sônia A., Silva, Thiago J. & Polizei, Thiago T. S., 2024, Description of larvae and redescription of the fungus beetle Pselaphacus procerus Kuhnt, 1910 (Coleoptera: Erotylidae: Erotylinae: Tritomini) from Brazil, pp. 73-92 in Zootaxa 5529 (1) on pages 75-90, DOI: 10.11646/zootaxa.5529.1.3, http://zenodo.org/record/14022031