Cercyon insularis Chevrolat, 1863

Arriaga-Varela, Emmanuel, Seidel, Matthias, Deler-Hernandez, Albert, Viktor Senderov, & Fikacek, Martin, 2017, A review of the Cercyon Leach (Coleoptera, Hydrophilidae, Sphaeridiinae) of the Greater Antilles, ZooKeys 681, pp. 39-93 : 57-63

Cercyon insularis Chevrolat, 1863 Figures 4 a–i, 12 a–i, 16c

Cercyon insulare Chevrolat, 1863: 208.

Cercyon insulare Gundlach (1891: 50, redescription).

DNA barcodes.

GANTC001-16, GANTC011-17, GANTC012-17

BIN ID.

BOLD:ADC9388.

Figures in Flickr.

www.flickr.com/photos/142655814@N07/albums/72157669492393134

Type locality.

Cuba: Havana.

Type material.

Holotype (unsexed specimen): "Havana, D. Poey // Cercyon insulare , Chev Cuba, [illegible] // TYPE [red label]" (MNHN).

Additional material examined.

CUBA: Camagüey: Sierra de Cubitas municipality, Limones-Tuabaquey, 21°35'52.10"N, 77°47'17.62"W, 16.v.2013, leg. R. Anderson (1 spec.: NMPC). Guantánamo: El Yunque, 3.2 km SW of campismo popular, at right tributary of Duabe river, secondary evergreen forest, cow excrement, 20°19'N, 74°34'W, 150 m a.s.l., 13.vi.2012, leg. Deler-Hernández & Fikáček (MF09) (7 spec.: NMPC); El Yunque, ca. 1.4 km W of campismo popular, cocoa plantations shaded by palms, cow excrement, 20°20.2'N, 74°33.7'W, 60-150 m a.s.l., 11.vi.2012, Deler-Hernández & Fikáček (MF03) (16 spec.: NMPC). Santiago de Cuba: El Vivero, 1.6 km E of Dos Caminos, cow excrements on pasture, 20°10.8'N, 75°46.4'W, 150 m, 20-21.vi.2012, leg. Deler-Hernández & Fikáček (MF18) (1 spec.: NMPC); San Luis Municipality, Dos Caminos, 20°10'57.82"N, 75°46'40.84"W, 3.x.2012, leg. Deler-Hernández (12 spec.: NMPC). Granma: PN Turquino, around La Platica, 20°0.7'N, 76°53.4'W, 880 m, 25-26.vi.2012, leg. Deler-Hernández & Fikáček (MF24) (12 spec.: NMPC); PN Turquino, on the trail up to 0.5 km S of La Platica, 20°0.5'N, 76°53.3'W, 920 m, 23-27.vi.2012, leg. Deler-Hernández & Fikáček (MF20) (2 spec.: NMPC); PN Turquino, La Siguapa, ca. 1.5 km SE of La Platica, sifting leaf litter in evergreen forest, 20°0.2'N, 76°52.8'W, 1290 m, 25.vi.2012, leg. F. Cala-Riquelme (MF25) (1 spec.: NMPC) [DNA extract at NMPC] (1: NMPC). Artemisa: Cañon de Santa Cruz, Río de Santa Cruz, 22°45'1.29"N 83°08'56.36"W, 199 m a.s.l., 16.vii.2016, leg. A. Deler-Hernández (1 spec.: NMPC) [DNA extraction: MF1749]. DOMINICAN REPUBLIC: La Vega: 7.0 km W of Manabao, side of a stony stream in a valley with scattered houses and plantations surrounded by montane forest, in cow excrements, 19°4.56'N, 70°51.46'W, 1185 m a.s.l., 23.viii.2014, leg. Deler-Hernández, Fikáček & Gimmel (DR18) (3 spec.: NMPC); at S margin of Manabao, 19°3.85'N, 70°47.61'W, 912 m a.s.l., 27.viii.2014, leg. Deler-Hernández & Fikáček (DR23) (3 spec.: NMPC). Samaná: MN Salto El Limón 2.8 km SSW of El Limón, secondary vegetation and tiny remnants of forests among coffee plantations and pastures, cow excrements, 19°16.56'N, 69°26.47'W, 2.ix.2014, leg. Deler-Hernández, Fikáček & Gimmel (DR29a) (16 spec.: NMPC). Monseñor Nouel: PN La Humeadora; 11.6 km SSW, of Piedra Blanca, in horse excrement in moist broad-leaf forest in a valley of a small stony stream, 18°44.92'N, 70°21.63'W, 636 m a.s.l., 8.ix.2014, leg. Deler, Fikáček & Gimmel (DR41) (4 spec.: NMPC) [DNA extracts: MF1214.1, MF1214.2]. PUERTO RICO: Naguabo: El Yunque National Forest (southern part), 3.45 km N of Río Blanco at road PR191, in horse excrements on exposed small pasture on the slope of El Yunque massive, 18°14.8'N, 65°47.9'W, 170 m a.s.l., 24.vi.2016, leg. Deler-Hernández, Fikáček & Seidel (PR2a) (19 spec.: NMPC) [DNA extraction: MF1731]; El Yunque National Forest (southern part), 4.9 km N iof Río Blanco, margin of the rainforest in an area with many flowering Etlingera elatior plants, FIT, 18°15.8'N, 65°47.3'W, 495 m a.s.l., 24.vi.-2.vii.2016, leg. Fikáček & Seidel (PR11) (3 spec.: NMPC). Arecibo: small settlement in Bosque Estatal Río Abajo, in the middle of the lowland forest, horse excrement, 18°19.7'N, 66°42.1'W, 340 m a.s.l., 27.vi.2016, leg. Deler-Hernández, Fikáček & Seidel (PR15) (1 spec.: NMPC). Lesser Antilles: DOMINICA: Springfield Estate, mature secondary forest, FIT, 15°20.796'N, 61°22.142'W, 30.v.-16.vi.2004, S. & J. Peck (04-86) (3 spec.: SBP). GRENADA: Grand Etang Forest Reserve, FIT in rainforest, 12°04.846'N 61°42.333'W, 360 m a.s.l., leg. S. Peck (10-61) (2 spec.: SBP); Grand Etang Forest Reserve, FIT in rainforest, 12°04.162'N 61°42.162'W, 400 m a.s.l., leg. S. Peck (10-63) (2 spec.: SBP); St. Andrew, Mirabeu Agriculture Lab, light trap, 19.iv.1990, leg. J. Telesford (2 spec.: SBP). SAINT LUCIA: Mon Repos, 6.5 km W Fox Grove Inn, submontane forest, carrion traps, 13°52.5'N, 60°56.4'W, 300 m a.s.l., leg. S. & J. Peck (0759) (2 spec.: SBP).

Published records

(as C. variegatus ). JAMAICA: without precise locality ( Smetana 1978). PUERTO RICO: without precise locality ( Smetana 1978). DOMINICA: without precise locality ( Leng and Mutchler 1917; Peck 2006).

Diagnosis.

Body size 2.4-3.4 mm; dorsal surface of head (Fig. 4a) black with a pair of small pale spots on vertex (sometimes fused in one central spot), pronotum yellowish to dark reddish-brown with a large blackish central spot and two small round blackish spots at sides (sometimes obscured); elytra yellowish with black humeral spot, in dark specimens whole elytral base and suture darkened; medial ridge of prosternum not projected ventrally (Fig. 12c); mesoventral plate narrow, 5.8 × as long as wide (Fig. 12f); metaventrite (Fig. 12g) without femoral lines, with raised pentagonal area as long as wide; first abdominal ventrite without spine-like process in both sexes (Fig. 12h); apex of fifth abdominal ventrite (Fig. 12i) without apical projection in both sexes; aedeagus narrow, parameres 0.7 × as long as phallobase (Fig. 4f), rounded at apex; median lobe (Fig. 4g) subparallel throughout except for acuminate apex, without subapical spines.

Redescription.

Body. (Fig. 4 a–d) 2.4-3.4 mm long (length of holotype: 2.8 mm); moderately elongate oval, 1.7 –1.8× as long as wide, widest at basal fifth of elytra; moderately convex, 2.6 –2.8× as long as high (height of holotype: 1.0 mm). Coloration. Dorsal surface of head black with a pair of small rufotestaceous spots on vertex. Antennal scape and flagellum and ventral surface of head including mouthparts light-brown, antennal club and mentum dark brown. Pronotum yellowish to dark reddish-brown, with a large blackish central spot and two small round blackish spots at its sides, sometimes connected with central spot. Prosternum yellowish to light brown, hypomeron slightly darkened. Elytra with elongate blackish spot posterior to humeri, elytral base and suture darkened, elytral epipleura uniformly pale. Ventral surface of mesothorax blackish. Metepisternum brown. Metaventrite blackish, darker at medial elevation. Abdomen yellowish to reddish-brown. Legs yellowish to light brown.

Head. Clypeus with moderately dense and shallow punctation consisting of small transverse punctures; interstices without microsculpture. Anterior margin of clypeus with narrow bead. Frontoclypeal suture conspicuous as a zone without punctuation, vanished mesally. Frons with punctation similar to that on clypeus, punctures sparser on sides; interstices without microsculpture. Eyes rather small, interocular distance about 6 × the width of one eye in dorsal view. Labrum membranous, nearly completely concealed under clypeus, only with narrowly exposed sinuate anterior margin. Mentum (Fig. 12a) subtrapezoid, widest at posterior fourth, about 2 × wider than long, 1.5 × wider at widest part than at anterior margin, strongly concave in anterior half, anterior margin not emarginate; surface almost glabrous, punctures small, shallow and sparse, almost vanishing anteromesally, interstices without microsculpture. Antenna with 9 antennomeres, scapus ca. 1.8 × as long antennomeres 2-6 combined; antennal club moderately elongate, about twice as long as wide, as long as scapus; antennomere 9 acuminate at apex.

Prothorax. Pronotum transverse, widest at base 2.1 –2.2× wider than long; 1.7 –1.8× wider at base than between front angles, 1.8 × wider than head including eyes, as convex as pronotum in lateral view. Punctation rather dense and moderately deep, consisting of crescent-shaped punctures intermixed with denser, slightly smaller and rather transverse punctures; punctures slightly feebler on sides. Prosternum (Fig. 12b) strongly tectiform medially, median ridge (Fig. 12c) with the same width throughout, anterior apex not projecting ventrally. Antennal grooves distinct, with lateral margin curved.

Pterothorax. Scutellar shield 1.2 × as long as wide, sparsely punctured. Elytra widest at anterior fifth, 1.0 –1.1× longer than wide, 2.6 –2.8× as long as pronotum, 1.2 –1.3× as wide as pronotum, surface glabrous, with 10 series of punctures; series 6, 8 and 9 not reaching anterior margin, surface glabrous (Fig. 12d), serial punctures getting slightly smaller lateraly; intervals moderately convex; punctation on interval 1 and odd intervals composed of crescent-shaped setiferous punctures, close to striae denser and intermixed with smaller, transverse non-setiferous punctures; even intervals with non-setiferous punctures only; all interstices without microsculpture. Humeral bulge indistinct. Mesoventral plate (Fig. 12f) narrowly elongate, ca. 5.8 × as long as wide, widest at midlength, symmetrically narrowing to both apices, anterior apex pointed, posterior apex rounded, posterior tip slightly overlapping over anterior portion of metaventrite; surface with few sparse punctures. Metaventrite (Fig. 12g) with raised pentagonal area ca. as wide as long, weakly, sparsely, uniformly punctated, without visible setae, bare part not reaching anterior margin of metaventrite; femoral lines absent; lateral parts of metaventrite densely covered by short pubescence.

Legs. Femora with sparse shallow punctures ventrally, interstices with weak microsculpture consisting of longitudinal lines; tibial grooves distinct. Tibiae with rather small lateral spines. Metatibiae moderately broad and long, straight, 0.33 × as long as elytra, 5 × as long as wide. Metatarsus long, 0.86 –0.89× as long as metatibia, with just a few short rather stout setae ventrally.

Abdomen with five ventrites, first abdominal ventrite (Fig. 12h) about as long as the second and third ventrites together, with distinct median longitudinal carina narrowing posteriad, not projecting posteriorly in both sexes; fifth ventrite with acuminate apex and weakly bulged in both sexes (Fig. 12i).

Male genitalia. Median projection of sternite 9 (Fig. 4i) rounded apically, with a pair of subapical setae, base symmetrical. Phallobase (Fig. 4f) almost 1.4 × longer than parameres, narrow, parallel sided, base widely rounded, manubrium indistinct. Parameres nearly of the same width in basal 3/4, divergent near apex, rounded and weakly narrowing apically. Median lobe (Fig. 4g) narrow and subparallel throughout, pointed at apex (Fig. 4h), gonopore moderately large, basal portion of median lobe with dorsal plate narrow and simply bifid basally.

Variability.

The general dorsal coloration of the pronotum and elytra varies from yellow to dark reddish-brown. In dark specimens, lateral pronotal spots join the large central spot, and the whole anterior part of elytra and the elytral suture are distinctly darkened, with pale areas maintained in humeral area and at sides of scutellar shield. In pale specimens, the lateral pronotal spots are rather small and sometimes very vague and indistinct, and the elytra are completely yellow except base, sutural interval and the posthumeral dark spots.

Distribution.

Cercyon insularis seems to be widely distributed across Greater and Lesser Antilles, here we are recording it from Cuba, Dominican Republic, Puerto Rico, Grenada, Saint Lucia and Dominica. It seems that all records of C. variegatus from the Caribbean (Jamaica, Puerto Rico: Smetana 1978; Dominica: Peck 2006) actually concern C. insularis , as we failed to find the true C. variegatus in the material examined. For that reason we consider C. insularis to occur in Jamaica, although we did not examine any specimens from Jamaica ourselves.

Bionomics.

Most of the specimens were collected in cow and horse dung on pastures, in coffee plantations and in tropical forests; few were collected using flight intercept traps.

Discussion.

Chevrolat (1863) described C. insularis based on a single specimen from Cuba collected by D. F. Poëy and deposited in Chevrolat's collection. On our request to loan this specimen, we received a single specimen standing under the name C. insularis in the Chevrolat collection, corresponding well with the original description and marked as a type. In contrast to the data mentioned by Chevrolat (1863), the specimen also bears a label indicating Habana as the place of its origin. Since there is no reason to doubt the type identity of this specimen, we correct the type locality of C. insularis to Habana, in agreement with the label data of the holotype.

Cercyon insularis was only briefly mentioned once by Gundlach (1891) and its type was not reexamined, therefore its identity remained unclear. Our inspection of the type revealed it corresponds by coloration with what was recorded from the Caribbean as Cercyon variegatus Sharp, 1882, by Smetana (1978), Hansen (1999) and Peck (2006). In order to determine the identity of the species present in the Caribbean we studied the lectotype of C. variegatus (Fig. 4 j–o, deposited in BMNH) and compared it to the type of C. insularis and additional recently collected material from Cuba. Based on this comparison, it became clear that Cuban specimens are not conspecific with C. variegatus , but belong to a different species indistinguishable from it by external morphology: all dissected Cuban specimens were conspecific, differed from C. variegatus by genital morphology, and no other species of the same external coloration was found. We hence consider the Cuban specimens conspecific with the type specimen of C. insularis , even though it cannot be dissected because of its poor condition. Both median lobe (Fig. 4g) as well as phallobase and parameres (Fig. 4f) are narrower in C. insularis than in C. variegatus . The apices of parameres are rounded in C. insularis , while they are more acuminate in C. variegatus (Fig. 4l). Moreover, the apex of the median lobe of C. variegatus has a small flank on each side (Fig. 4n) (Full set of pictures of the lectotype of C. variegatus in www.flickr.com/photos/142655814@N07/albums/72157676248390724).

Cercyon insularis and C. variegatus belong to a species complex corresponding to the C. variegatus group of Smetana (1978), distributed from the southern USA to Argentina; the species within this complex can be only distinguished by the morphology of the male genitalia (Arriaga-Varela and Fikáček, pers. observation). Only two species of this species complex have been formally described ( C. variegatus and C. insularis ) and the group requires a detailed revision. The species recorded from Suriname as " Cercyon rishwani " by Makhan (2004) also belongs to this species complex based on color pattern of the pronotum and the general shape of the aedeagus, but a more detailed comparison with C. insularis and C. variegatus is impossible based on the description and illustrations provided. " Cercyon rishwani Makhan, 2004" is moreover considered a nomen nudum (see Short and Hebauer, 2006 for details).