Cercyon (Cercyon) curi, Clarkson & Mise & Almeida, 2020

Clarkson, Bruno, Mise, Kleber M. & Almeida, Lucia M., 2020, Cercyon Leach, 1817 (Coleoptera: Hydrophilidae: Sphaeridiinae) from Brazil: new species and records, Revista Brasileira de Entomologia (e 201972) 64 (1), pp. 1-8 : 2-6

Cercyon (Cercyon) curi sp. nov.

( Figs. 1 A-C, 2A-D and 3A-F)

Type locality. Brazil, Guarapuava Municipality , Paraná State, Est. Águas Santa Clara

Type Material. Holotype (male): “ Guarapuava - Paraná / Est. Águas Sta. Clara / BRAZIL 30. I. 1987 / Lev.Ent.PROFAUPAR/ LÂMPADA” ( DZUP) ; Paratypes (230 exs.): BRAZIL: Paraná: Antonina: “ANTONINA -PR/ Reserva Spitanduva / BRASIL 25. IV. 1987 / Lev. Ent. PROFAUPAR/ LÂMPADA” (8 exs.: DZUP) ; same data, different dates, all specimens deposited in DZUP: “ 30. XI. 1986 ” (1 ex.) ; “ 01. XII. 1986 ” (1 ex.) ; “ 03. XII. 1986 ” (1 ex.) ; “ 20. IV. 1987 ” (1 ex.) ; “ 31. I. 1987 ” (1 ex.) ; “ 30. III. 1987 ” (1 ex.) ; Colombo: “ COLOMBO - PR / EMBRAPA BR 476 km 20/ BRASIL 01.III.1987 / Lev. Ent. PROFAUPAR/ LÂMPADA” (2 exs.: DZUP) ; same data, different date: “ 30. I. 1987 ” (1 ex.: DZUP) ; Curitiba: “Curitiba-PR (BR)/ Centro Politécnico / Bandeja / 07/X/2005 / Mise, K. M. ” (1 ex.: DZUP) ; same data, different dates, all specimens deposited in DZUP: “ 13/X/2005 ” (1 ex.) ; “ 24/XI/2005 ” (1 ex.) ; “ 30/XI/2005 ” (1 ex.) ; “ 31/I/2006 ” (1 ex.) ; Fênix: “ FÊNIX - PARANÁ / Reserva Est - ITCF / BRASIL 27. III.1987 / Lev.Ent. PROFAUPAR/ LÂMPADA” (101 exs.: DZUP; 5 exs.: MNRJ; 5 exs.: MZSP; 5 exs.: NMPC; 5 exs.: SEMC; 5 exs.: CEMT) ; same data, different dates, all specimens deposited in DZUP: “ 28.III.1987 ” (16 exs.) ; “ 29. II.1987 ” (1 ex.) ; Guarapuava: Same data as Holotype (5 exs.: DZUP) ; same data, different dates, all specimens deposited in DZUP: “ 29.XI.1986 ” (4 exs.) ; “ 01.XII.1986 ” (2 exs.) ; “ 02.XII.1986 ” (2 exs.) ; “ 30.XII.1986 ” (1 ex.) ; “ 01. I.1987 ” (8 exs.) ; “ 25. II.1987 ” (1 ex.) ; Jundiaí do Sul: “JUNDIAÍ DO SUL - PR / Fazenda Monte Verde / BRASIL 30. XI. 1986 / Lev. Ent. PROFAUPAR/ LÂMPADA” (1 ex.: DZUP) ; same data, different dates, all specimens deposited in DZUP: “ 03. XII. 1986 ” (3 exs.) ; “ 30. XII. 1986 ” (3 exs.) ; “ 01. I. 1987 ” (5 exs.) ; “ 02. I. 1987 ” (2 exs.) ; “ 29. I. 1987 ” (1 ex.) ; “ 30. I. 1987 ” (2 exs.) ; “ 27. II. 1987 ” (1 ex.) ; “ 01. III. 1987 ” (1 ex.) ; “ 26. IV. 1987 ” (12 exs.) ; “ 27. IV. 1987 ” (8 exs.) ; “ 25. V. 1987 ” (1 ex.) ; São José dos Pinhais : “S. JOSÉ PINHAS - PR / Ser. do Mar BR277 Km54 / BRASIL 29. VII. 1987 / Lev.Ent. PROFAUPAR/ LÂMPADA” (1 ex.: DZUP) ; Telêmaco Borba: “TELÊMACO BORBA - PR / Res. Samuel Klabin / BRASIL 28. II. 1987 / Lev. Ent. PROFAUPAR/ LÂMPADA” (2 exs.: DZUP) .

Diagnosis. Small to medium sized species (2.00– 2.55 mm in length); dorsal surface of head dark brown to black, posterocentral area on frons often lighter, brown in front of eyes and in the anterior margins of clypeus ( Fig.2A ); pronotum with two lateral and one central large fused black spots, diffuse, brown to pale brown at posterior and lateral portions; elytra pale brown to yellow, darker along sutural area and in the apical margin; with moderate sized black spots on anterolateral portions, black at basal margins, pale in the humeral humps ( Fig. 1A and C ); prosternal medial ridge thickened anteriad; mesoventral plate ( Fig. 2D ) narrowly elongate, ca. 5.9× as long as wide, pointed posteriorly; metaventrite ( Fig. 2D ) without femoral lines, with narrow raised pentagonal area, 1.1× as long as wide; first abdominal ventrite not projecting posteriorly in both sexes ( Fig. 3A ); apex of fifth abdominal ventrite slightly acuminate apex, weakly bulged in both sexes ( Fig. 3A ). Sternite 9 ( Fig. 3B ) asymmetrical basally, with median process narrow and short, widely acuminate at apex, without subapical setae; phallobase ( Figs. 3C–E ) almost twice as long as parameres, slightly asymmetrical at base; parameres in dorsal view narrow, inner margins somewhat concave, in ventral view inner margins are extended inwardly, somewhat convex; apex acuminate and narrowly rounded, turned inwardly, without setae ( Figs. 3 C-E); median lobe ( Figs. 3D and F ) abruptly constrict at apical fourth, acuminate at apex, without subapical spines; sigmoid shaped in lateral view ( Figs. 3C ).

Description. Holotype male.

Size and form. Total length 2.18 mm; maximum width 1.38 mm; maximum width of the head 0.70 mm; elytral length 1.64 mm; maximum width of the pronotum 1.20 mm; maximum height 1.00 mm.Body oval, moderately convex ( Figs. 1 A-C).

Coloration. Dorsal surface of head dark brown to black, posterocentral area on frons often lighter; posterolateral portion of clypeus (in front of eyes), and anterior margins brown ( Fig. 2A ). Pronotum with two lateral and one central large fused black spots, almost reaching anterior margin, with posterior and lateral surfaces brown to pale brown; limits of spots diffuse ( Figs. 1A and C ). Elytra pale brown to yellow, slightly darker on elytral disc (on interstriae 1–6) from elytral base until ca. of apical quarter, conspicuously darker along sutural area and in the apical margin; with moderate sized black spots on anterolateral portions (anterior quarter); black at anterior margins; pale in the humeral humps ( Fig. 1A and C ). Ventral surface of head brown; antennomeres 1 to 6 light brown to yellow, distal club brown; labial and maxillary palps light brown ( Figs. 1B , 2A and B ). Ventral face of thorax and abdomen brown to dark brown. Legs brown, pro and mesotarsus lighter ( Fig. 1B ).

Head.Labrum membranous, nearly completely concealed under clypeus, only with narrowly exposed sinuate anterior margin ( Figs. 2A and B ). Clypeus with rather coarse and dense punctuation, distance between punctures ca. 1.0–2.0× the width of one puncture, shallowly impressed, consisting of crescent-shaped setiferous punctures intermixed with dense, crescent-shaped non-setiferous punctures, about the same sized of setiferous; interstices without microsculpture. Anterior clypeal margin with a narrow bead ( Figs. 2A and B ). Frontoclypeal suture inconspicuous ( Fig.2A ). Frons with punctation similar to that on clypeus, punctures sparser on sides; interstices without microsculpture. Eyes rather small; interocular distance about 5× the width of one eye in dorsal view ( Figs. 2A and B ). Mentum subtrapezoid, widest at posterior fourth, about 1.5× wider than long, 1.8× wider at posterior margin than anterior margin, concave in anterior half, with a shallow transverse impression anteromesally; surface glabrous, punctures rather coarse and shallow, interstices slightly rugose. Antenna with 9 antennomeres, scapus about 2× as long as antennomeres 2-6 combined; antennal club broad, pubescent and about the same length as scapus, antennomere 9 barely acuminate at apex ( Figs. 1B , 2A ).

Prothorax. Pronotum transverse, widest at base 2.1–2.2× wider than long; 1.4–1.5× wider at base than between anterior angles, 1.7× wider than head including eyes, as convex as the elytra in lateral view ( Fig.1A ). Punctation on pronotal disc homogeneously distributed on surface, moderately dense and shallow, consisting of crescent-shaped punctures intermixed with slightly smaller and rather transverse punctures; punctures slightly feebler on sides; distance between punctures ca. 1.0–3.0× the width of one puncture; punctures with decumbent setae scattered on pronotal disc ( Fig. 2C ). Prosternum strongly tectiform medially, medial ridge thickened anteriad, forming a small rounded to slightly pointed process. Antennal grooves distinct, with curved external margins, well-marked anteriorly ( Fig. 2B ).

Pterothorax. Scutellar shield 1.4× as long as wide, sparsely punctured ( Fig. 2C ). Elytral surface glabrous, except for scattered small systematic punctures (trichobothria) set with very short decumbent setae. Elytron with 10 punctural series, well-marked, forming longitudinal striae; series 6–10 not reaching elytral base; series 10 shortened posteriorly, reaching half of the elytral length, lying parallel to elytral margin ( Figs.1A and C ). Serial punctures of the same size in the series 1–6; slightly larger in the series 7–10; intervals weakly convex ( Figs. 1A and C ); interval punctation composed by crescent-shaped punctures intermixed with denser, slightly smaller and rather transverse punctures in all intervals. Humeral hump slightly prominent ( Fig. 1A ). Elytral epipleura wide ( Fig. 1B ) Mesoventral plate ( Fig. 2D ) narrowly elongate, ca. 5.9× as long as wide, widest in at midlength, strongly narrowed in the anterior and posterior apices, which are pointed, posterior tip sharply acuminate, overlapping over anterior portion of metaventrite; surface with a few sparse coarse punctures. Metaventrite ( Fig. 2D ) with narrow raised pentagonal area, 1.1× longer than wide, glabrous, weakly and sparsely punctuate, punctures with fine setae at least along margins of the elevation; bare elevated area not reaching anterior margin of metaventrite; punctures absent at two slightly elongate areas in the center; femoral lines absent; lateral parts of metaventrite densely covered by short pubescence.

Legs. Meso and metafemora with sparse rather shallow punctures, interstices with very weak microsculpture on ventral face, consisting of longitudinal lines, this microsculpturation is more evident along anterior margins of femora; tibial grooves distinct. Tibiae with rather small lateral spines. Metatibiae moderately narrow and elongate, straight, 0.3× as long as elytra, 5× as long as wide. Metatarsus ca. as long a metatibia, with short rather stout setae ventrally. Last tarsomere of each tarsus with long setae ventrally.

Abdomen. First abdominal ventrite about as long as the second and third ventrites together, with distinct median longitudinal carina narrowing posteriad, not projecting posteriorly in both sexes ( Fig.3A ); fifth ventrite with slightly acuminate apex, weakly bulged in both sexes ( Fig. 3A ).

Male genitalia. Sternite 9 ( Fig. 3B ) asymmetrical basally, median process narrow and short, ca. as long as half of lateral struts, slightly widening apically, widely acuminate at apex, without subapical setae. Phallobase ( Figs. 3C–E ) narrow and long, ca. 2.9× longer than wide, almost twice as long as parameres, widely rounded at basal margin, slightly asymmetrical at base, manubrium indistinct. Outer margins of parameres very weakly concave, almost subparallel sided; parameres in dorsal face narrow, inner margins continuously narrowing apically until the distal thirds of parameres, which the apex bent inwardly, giving a concave shape, in ventral face parameres extended inwardly, inner margins contiguous and subparallel until the distal thirds of parameres, which the outline bends outwards, convex anteriorly, merging with dorsal portion subapically, without setae; apex acuminate and narrowly rounded, turned inwardly, without setae ( Figs. 3C–E ). Median lobe ( Figs. 3D and F ) widest at midlength, slightly narrowing towards base, abruptly constrict at apical fourth, widely narrowing into an acuminate, widely pointed apex, without subapical spines; sigmoid shaped in lateral view ( Fig. 3C ); gonopore moderately large, subapical; basal portion with dorsal plate narrow and simply bifid basally.

Variation. The examined specimens vary in body size (from 2.00 mm to 2.55 mm in length).The general dorsal coloration varies in non-teneral specimens: dark areas can be dark-brown to black while light areas can be pale-yellow to light-brown or “testaceous”; frons is completely dark or slightly lighter in the posterocentral area (as in Fig. 2A ); dark area in pronotum can be more or less developed; in paler specimens the elytra are completely yellow except base, sutural interval, and the anterolateral spots; in darker specimens the whole anterior part of elytra, from base until ca. of apical quarter, and the elytral suture are distinctly darkened, with pale areas maintained in humeral area and at sides of scutellar shield; elytral longitudinal striae can have the same coloration of the elytral surface, can be slightly darker than elytral surface and slightly distinct by coloration (as in Fig. 1A ) or dark brown to black, distinct from elytral surface by coloration.There is not evident sexual dimorphism in the external morphology.

Etymology. The specific epithet curi is a Tupi-Guarani aboriginal word that means “pine tree”. It is a reference to the characteristic conifer tree Araucaria angustifolia (Bertol.) Kuntze, 1898 preponderant in the mixed ombrophilous Atlantic rain forest and typical of the Paraná State. The name is used as a noun in apposition.

Distribution. Brazil, Paraná State: Antonina , Colombo , Curitiba, Fênix, Guarapuava, Jundiaí do Sul, São José dos Pinhais and Telêmaco Borba municipalities ( Fig. 4 ).

Bionomics. Most of the examined specimens were collected using light as indicated in their labels with the word “LÂMPADA” which means “lamp” in Portuguese but five specimens from Curitiba municipality were collected in pig carcass in a controlled forensic experiment of entomological succession during putrefaction and butyric fermentation stages.

Discussion. The new species belongs to the subgenus Cercyon (s. str.) as defined by Smetana (1978) that is characterized by having the middle portion of prosternum simply elevated to form longitudinal median keel (tectiform), not differentiated laterally from antennal grooves of prothorax which are therefore completely open medially ( Fig. 2B ); elevation of mesoventrite narrowed posteriorly, contacting the elevated middle portion of metaventrite at a single point ( Fig. 2D ); and the pronotum and elytra together convex in lateral view, forming continuous outline ( Fig. 1C ). Inside Cercyon (s. str.) the new species seems to be closely related withCercyon insularis Chevrolat, 1863 and C.variegatus Sharp, 1882 based on similarities in the external morphology – as coloration pale with distinctive dark pattern ( Figs. 1A–C ); dorsal surface glabrous, without evident microsculpture; elytral epipleura wide ( Fig. 1B ); elevated middle portion of mesoventrite narrow and elongate, its posterior part contacting metaventrite; and metaventrite without femoral lines ( Fig. 2D ) – and in the general shape of the aedeagus – with long and narrow phallobase widely rounded at base with manubrium indistinct ( Figs. 3C–E ).

Based on these characteristics, Cercyon curi sp. nov. should belong to the species complex corresponding to the C. variegatus group of Smetana (1978), distributed from the southern USA to Argentina.The new species can be distinguished from C.insularis and C.variegatus mainly by characteristics of the male genitalia ( Figs.3B–F , see Arriaga-Varela et al., 2017: Fig. 4 for detailed illustration of C. insularis and C. variegatus ) which the sternite 9 ( Fig. 3B ) is asymmetrical basally, with median process short, ca. as long as half of lateral struts, widely acuminate at apex, without subapical setae (symmetric basally, with median process longer than half of lateral struts, rounded apically, with a pair of subapical setae in C. insularis and C. variegatus ); phallobase is slightly broader (ca. 2.9× longer than wide) than in C. variegatus (ca. 3.8× longer than wide) and distinctly broader than in C. insularis (ca. 5× longer than wide); phallobase is only slightly asymmetrical at base in C. curi sp. nov. (the asymmetry at the base in C. insularis and C. variegatus is more evident); parameres narrower in dorsal face, with the inner margins continuously narrowing apicad until the distal thirds, the apex bent inwardly giving a concave shape to inner outline (inner margins of parameres in dorsal face is continuously narrowing apicad until the subapical portion, and the apex is pointed, abruptly bent inwardly in C. variegatus ; the parameres are subparallel-sized and widely rounded at apex, slightly turned outwards distally in C. insularis); in ventral face the parameres are extended inwardly with the inner margins contiguous and subparallel until the distal thirds of parameres, which the outline bends outwards, giving a convex aspect anteriorly, without setae (parameres are not extended in this way in C. insularis; in C. variegatus the parameres are also extended inwardly but the inner margins are not contiguous, tapering outwards until the distal thirds of parameres, which shortly bends outwards, giving an angulate aspect anteriorly, anterior margin of the projected portion with setae); as in C. insularis, the new species does not have setae at paramere apex (with setae at apex in C. variegatus ); the median lobe in C.curi sp. nov. ( Figs. 3D and F ) is constricted at apical fourth, widely narrowing into an acuminate widely pointed apex (median lobe is subparallel throughout and simply pointed at apex in C. insularis and is also subparallel throughout, and acuminate at apex but has a small flank on each side).

Besides C. curi sp. nov., C. insularis and C. variegatus the species recorded from Suriname as “ Cercyon rishwani ” by Makhan (2004) also belongs to the C. variegatus complex based on color pattern of the pronotum and the general shape of the aedeagus, but a more detailed comparison is impossible based on the description and illustrations provided. “ Cercyon rishwani Makhan, 2004 ” is moreover considered a nomen nudum ( Short and Hebauer, 2006; Arriaga-Varela et al., 2017).

Figures

Figure 1. Cercyon curi sp. nov. Habitus, (A) dorsal view, (B) ventral view, (C) lateral view, scale = 1.0 mm.

Figure 2. Cercyon curi sp. nov. (A) head in dorsal view, scale = 0.5 mm; (B) head in frontal view and prosternum, scale = 0.25 mm; (C) pronotal disc and scutellum sculpture, scale = 0.2 mm; (D) mesoventral plate and metaventral elevation, scale = 0.25 mm.

Figure 3. Cercyon curi sp. nov. Abdomem,(A) abdominal ventrites,scale = 0.5 mm; terminalia (B–F), (B) sternite 9; aedeagus (C–F),(C) lateral view;(D) dorsal view;(E) Phallobase and parameres in dorsal view; (F) median lobe in dorsal view, scale = 0.2 mm.

Figure 4. Map with the known distribution of Cercyon curi sp. nov., Cercyon inquinatus Wollaston,1854, Cercyon nigriceps (Marsham,1802) and Cercyon (Cercyon) praetextatus (Say, 1825) in South America based on d’Orchymont (1939), Fikáček (2009) and the current work. White square highlights the region of Paraná State where most part of the examined specimens is from.