Platycesta depressa ( Clark, 1865 ) Viswajyothi & Clark, 2021

Viswajyothi, Keezhpattillam & Clark, Shawn M., 2021, A New Genus to Accommodate Central and South American Beetles with Broadly Explanate Elytra, Formerly Assigned to Monocesta Clark and Coelomera Chevrolat (Coleoptera: Chrysomelidae: Galerucinae: Galerucini), The Coleopterists Bulletin 75 (2), pp. 473-484 : 474-483

Platycesta depressa ( Clark, 1865) , new combination ( Figs. 1–5 )

Monocesta depressa Clark 1865: 267 (type locality: “river Magdalina” [probably Río Magdalena, Colombia; see Jacoby 1886: 478]).

Monocesta nicaraguensis Jacoby 1877: 520 (type locality: “ Chontales, Nicaragua ”) (synonymy with M. depressa established by Jacoby 1886: 478).

Coelomera atro-caerulea Jacoby 1878: 152 (type locality: “ Peru, Panama ”), new synonymy.

Coelomera atrocaerulea : Blackwelder 1946: 687. Coelomera atrocoerulea : Wilcox 1971: 27.

Diagnosis. As this genus contains only a single known species, the genus diagnosis above is sufficient to enable species recognition. However, it is noteworthy that the head, prothorax, and scutellar shield are all largely or entirely yellow-brown to orange-brown. The antennae, tibiae, tarsi, and abdomen are all largely or entirely black. The elytra vary in color, from entirely orange-brown ( Fig. 2A ) to entirely black ( Fig. 1A ), with those of intermediate specimens being pale in the basal half and dark in the distal half ( Fig. 2C ).

Redescription. Body broadly ovate ( Figs. 1A , 2A, C ); male 8.7–11.5 mm long, 6.3–6.6 mm wide; female 9.9–13.2 mm long, 6.6–7.5 mm wide. Head and prothorax yellow-brown to orange-brown; elytra orange-brown to black (see variation section below); metaventrite and abdomen largely or entirely black; antennae largely or entirely black; femora orange-brown to black; tibiae and tarsi black.

Head yellow-brown to orange-brown; distal edge of labrum darker brown; distal half of mandible black.Vertex with punctures like those on central area of pronotum, finer than those at lateral areas of pronotum; surface of vertex finely alutaceous in flattened central area, more shiny laterally; coronal suture indicated by darker line, not impressed ( Figs. 1D , 2D ); setae uniformly distributed, dense, short, appressed, those in flattened central area slanting in anterolateral direction away from meson, those in more lateral areas slanting anteriorly; several longer, erect setae present near each eye. Eyes oval, each 1.25 times as long as broad, finely facetted, almost reaching antennal fossa; interocular distance 0.6 times width of head across eyes. Supracallinal sulcus semicircular behind each tubercle, deeply impressed; antennal calli alutaceous, sparsely pubescent, delimited posteriorly by abrupt supracallinal sulcus, mesally by midfrontal sulcus, anteriorly by dorsal edge of antennal fossae, and laterally by faint supraorbital sulcus. Frontal ridge continuous with antennal calli, mesally sulcate; anterofrontal ridge transverse, abruptly declivous in front, densely punctate and pubescent, with punctures clearly coarser than those of vertex. Frontoclypeal suture bordered by long sparse setae, extending almost to and beyond basal fourth of labrum; clypeus smooth, shiny, covering posterior portion of labrum, slightly shorter laterally, wider than labrum, as wide as distance between lateral edges of antennal fossae. Ventrolateral area, below and behind eye, with elon- gate patch of numerous erect setae, longer and sparser than those on central area of vertex; areas both anterior and posterior to patch glabrous, shining. Gena deeply sinuate near base of mandible, short, with length subequal to maximum width of second antennomere.

Labrum nearly rectangular, distinctly wider than long, narrower than distance between lateral edges of antennal fossae; surface alutaceous; scattered long setae present, extending far beyond anterior edge of labrum; distal edge truncate, slightly concave, with slender, short setae. Mandible basally alutaceous, distally shiny, projecting beyond labrum, appearing in two sections that are separated by deep sulcus; basal section yellow-brown, with long setae laterally, with distal edge dark brown to black; distal section completely black, triangular, at right angle to basal section, tapering towards apex, with apex sharp. Maxillary palpi pale yellow; pen- ultimate and antepenultimate palpomeres widened anteriorly, with long setae towards distal half of each; antepenultimate palpomere longest; apical palpomere slightly darker, slender, tapering anteriorly, differing from previous two palpomeres in absence of long setae.

Antenna extending to near middle of elytra, nearly filiform, but with distal antennomeres narrower. Surface densely covered with short, appressed setae ( Fig. 3A ); distal four antennomeres additionally with longer, erect setae. Basal antennomere 2.5–3.0 times longer than antennomere 2, gradually, slightly widening towards apex; antennomere 2 shortest, nearly as wide as long, narrower than antennomere 1; antennomere 3 longest, 1.6 times as long as antennomere 4; in male, greatest width of antennomere 3 slightly more than greatest width of antennomere 1; in female, greatest widths of antennomeres 1 and 3 subequal; antennomere 4 subequal in length with antennomere 1; antennomeres 5–10 each slightly shorter than antennomere that precedes it; antennomeres 8–11 each slightly narrower than antennomere that precedes it; antennomere 11 apically pointed, 1.6 times as long as antennomere 10.

Pronotum 1.9 times as wide as long, widest at anterior third, with greatest width 1.6 times wider than head, with posterior part 1.3 times wider than head; greatest length in lateral fourth. Anterior edge concave, with obtuse anterolateral corners extending anteriorly ( Fig. 1D ); posterior edge nearly straight, only slightly sinuate laterally; all four sides with very fine marginal bead and with dense row of short setae. Posterior corners narrowly rounded; all four corners with small seta-bearing pore. Disc with impression present on each side, extending nearly from posterior edge to apex, each covering about one-third of pronotal surface; mesal impression also present, triangular,extending from posterior edge to about mid-length; surface alutaceous, densely covered with short setae, densely, finely punctate in central area, more coarsely punctate laterally ( Figs. 1D , 2D ). Scutellar shield tongue-shaped, concolorous with pronotum, alutaceous, less roughly punctate than elytra.

Elytra 7.4–9.0 mm long in male, 8.1–9.9 mm long in female, 5 times as long as greatest length of pronotum, together about twice as wide as head; elytral base 1.4 times wider than greatest width of pronotum ( Figs. 1A , 2A, C ). Humeri well developed; basal calli obsolete, not delimited behind by depression; lateral areas broadly explanate. Epipleuron extremely broad at basal third, broader than maximum width of hind femur ( Fig. 2E ). Disc densely, finely punctate, densely covered with shiny, appressed, posteriorly directed setae.

Ventral areas of thorax mostly dark brown to black, except pro- and mesothorax and sometimes distal ventrite yellow-brown to orange-brown ( Figs. 1C , 2B ); pubescence dense, except on lateral areas of prothorax; mesothorax shining.Abdomen densely pubescent; dark brown to black, with last ventrite of some specimens yellow-brown to orange-brown; posterior edge of last ventrite entire in female ( Figs. 3B , 4F ), slightly sinuate in male ( Figs. 3C , 5G ); last external tergite without channel in either sex ( Figs. 4D , 5E ); last tergite (internal) without channel, with long setae on distal edge ( Figs. 4G , 5F ). Legs densely setose, at least partially dark brown to black.

Median lobe of aedeagus slightly asymmetrical in dorsal view ( Fig. 5A ); length 2.1 mm; at broadest part (distal third), 0.6 mm wide ( Fig. 5A ); distal fourth strongly narrowed to apex in dorsal view, more gradually narrowed to acute apex in orificial view ( Fig. 5C ); apex with small ogival projection ( Fig. 5C ); orifice occupying distal two-thirds of dorsal surface; in lateral view, median lobe nearly evenly curved, thickest (0.4 mm) at basal fourth, gradually narrowed from mid-length to apex ( Fig. 5B ), Endophallus without sclerites. Spiculum bifurcate in nearly distal third ( Fig. 5D ).

Female genitalia as in Fig. 4A . Spermathecal pump and receptacle distinct; receptacle nearly spherical, 0.3 mm wide, 0.2 mm long; pump curved in basal third, with maximum width 0.1 mm ( Fig. 4B ). Vaginal palpi short, slender, separated from each other by membrane, apically setose; length 0.4 mm; width at base 0.16 mm; width at apex 0.1 mm ( Fig. 4C ). Tignum 1.24 mm long; apical edge bisinuate, setose ( Fig. 4E ).

Variation. As noted in the above description, specimens vary in length, from 8.7 to 13.2 mm. In addition, the elytra vary from completely yellow-brown or orange-brown ( Fig. 2A ) to completely black ( Fig. 1A ). In specimens with completely black elytra, the terminal abdominal ventrite is entirely pale. In many specimens, the distal half of the elytra is dark, and the basal half is pale ( Fig. 2C ). Other color variations involve the last abdominal ventrite, which is entirely pale ( Fig. 3C ) to entirely black; some specimens are intermediate, such as those with only the posterior portion pale ( Figs. 3B ). These color differences are somewhat correlated with distribution, as detailed in the Material Examined section below. Although not detailed in the section below, the femora and the basal portion of the antennae also vary in color, from entirely dark to entirely pale, and some specimens are intermediate.

Material EXamined. In this section, the specimens are grouped according to color patterns. However, this may give the false impression that the differences among groups are discrete. In reality, although the specimens are listed in the group in which they fit best, many of them are intermediate. Note also that only the main color forms are distinguished in these lists. Other variations, such as those involving the leg color, are not indicated.

Entirely pale elytra ( Fig. 6 ). HONDURAS: Olancho: Sierra de Agalta , above 1,000 m, 6–9 June 1995, S. A . Wells (2, BYUC) ; Santa Bárbara: La Cumbre, 7-VI-2003, R . Turnbow (1, EGRC); unknown department: Liberia [locality not found, possibly a misprint for Siberia (Departamento de El Paraíso)], 2-IX-1984, C. W . O’Brien, rain forest (1, EGRC) .

Basal half of elytra pale, terminal ventrite completely black ( Fig. 7 ). COSTA RICA: Alajuela: 2.6 km E Buenos Aires , 10.8963°N, 85.2886°W, 3-III-2017, S. M . Clark & R. L . Johnson (1, BYUC); 20 km S Upala , June 1990, F . D. Parker (2, BYUC); same data except 27 Sept.–18 Oct. 1990 (1, BYUC); same data except 13 Dec. 1990 – 9 Jan. 1991 (2, BYUC); same data except 20 Jan.–12 Feb. 1991 (1, BYUC); same data except 5–18 Mar. 1991 (1, BYUC); same data except 10–21 May 1991 (1, BYUC); same data except 10–29 May 1991 (2, BYUC); same data except 1–11 June 1991 (2, BYUC); same data except 1–10 Aug. 1991 (1, BYUC); same data except 21–31 Aug. 1991 (1, BYUC); same data except 1–25 Sept. 1991 (1, BYUC) . Guanacaste: 3 km SE R . Naranjo, 1–15 June 1992, F . D. Parker (1, BYUC); same data except 1–10 Feb. 1993 (1, BYUC); same data except 14–21 June 1993 (1, BYUC); same data except 1–15 Aug. 1993 (1, BYUC); same data except 14–20 Aug. 1993 (1, BYUC) . Heredia: Est. Biol. La Selva , 11–13 Jan. 1995, E. G . Riley (1, TAMU); Estación Biológica La Selva , 12-I-1995, S. M . Clark (3, BYUC); Estación Biológica La Selva , 14-IV-2003, S. M . Clark & E. G . Riley (1, BYUC); La Selva Biol. Sta., 3 km S Pto.Viejo , 10°20′N, 84°01′W, 22-VI-1991, G . Gentry (1, TAMU); La Selva Res. Sta., 11–17 June 1986, D. J . Keller (1, BYUC) .

Basal half of elytra pale, apex of terminal ventrite yellow or brown ( Fig. 8 ). COSTA RICA: Alajuela: Bijagua, 20-I-1991, D. Thomas & F . Parker (1, EGRC); 20 km S Upala , 20–26 Mar. 1991, F . D. Parker (1, BYUC) . Guanacaste: Palo Verde, 22–30 Jan. 1975, J . Aldrich (1, EGRC); 3 km SE R . Naranjo, 4–8 Jan. 1993, F . D. Parker (1, BYUC) . Heredia: Estación Biológica La Selva , 12- I-1995, S. M . Clark (3, BYUC; 1, TIC); Estación Biológica La Selva , 10°25′N, 84°00′W, 12-III-2005, S. M . & D. R. Clark (1, BYUC; 1, TIC); Est. Biol. La Selva , 11–13 Jan. 1995, E. G . Riley (3, TAMU); Est. Biol. La Selva , 10°26′N, 84°01′W, 50–150 m, 20–31 May 1998, L. M . LaPierre (1, BYUC); Est. Biol. La Selva , 10°26′N, 84°01′W, 50–150 m, 9-III-2003, D. Furth & K . Zhaurova, exper. plots (1, TAMU); La Selva Biol. Stn., 13-I-1995, C. L. & S. L . Staines (1, BYUC); La Selva Biol. Sta., 2 km S Pt. Viejo , 21–22 Jan. 1987: J . Negrón (1, EGRC); La Selva Res. Sta., 24–30 Aug. 1988, W. J . Hanson (1, BYUC); 11 km ESE La Virgen , 10°20′N, 84°03′W, 250–350 m, 18-IV-2004, INBio-OETALAS transect, Malaise, 03/ M/19 / 099, INB0003616545 (1, INBio) ; 11 km SE La Virgen , 10°20′N, 84°04′W, 450–550 m, 23-III-2003 ,

INBio-OET-ALAS transect, transect 05/ M/10 / 050, INB0003236794 (1, INBio) . Limón: Tortuguero , 22-VIII-1968, M. J . Corn (1, TAMU) .

Basal half of elytra pale, majority of terminal ventrite yellow or brown ( Fig. 9 ). COSTA RICA: Guanacaste: Limón: Pandora, 150 ft., 22-VIII-1963, S. L . Wood (1, BYUC); 3 km SE R Naranjo, 20–31 Aug. 1992, F . D. Parker (1, BYUC); same data except 13–31 July 1993 (1, BYUC) . PANAMA: Chiriquí: Fortuna, 82°15′W, 8°44′N, 17-V-1978, O’Briens & Marshall (1, BYUC); Res. For. La Fortuna , El Vivero, 19-VII-1995, C. W. & L. B . O’Brien (1, BYUC) . Bocas del Toro: 4 rd. km. N cont. div. on Gualaca-Chir. Gr. Hwy., 14-VI-1985, E . Riley & D. Rider (1, EGRC); Reserva La Fortuna , trail nr. trailhead of Divide Trail, 28-V-1993, E. G . Riley (1, EGRC) .

Entirely black elytra, terminal ventrite entirely pale ( Fig. 10 ). COSTA RICA: Guanacaste: Puerto Humo , 17-VIII-1966, F . Fisk (1, BYUC) . Puntarenas: Monteverde , 26 May–3 June 1984, E . Riley, D. Rider & D. LeDoux (1, EGRC); Puerto Jiménez, 8°32′N, 83°19′W, 10m, Feb. 1991, P . Hansen , Malaise trap, weedy patch (1, BYUC); Rincón, Osa Pen., 100 ft., 11-VIII-1966, S. L . Wood (1, BYUC); Rincón de Osa , 31-VII-1966, D. F . Veirs (1, BYUC); 9 km NW San Vito, 21-IV-2003, S. M . Clark & E. G . Riley (1, BYUC) . San José: Río Damitas , 700 ft., 22-VIII-1963, S. L . Wood (1, BYUC) . ECUADOR: Manabí: Río Suma , 3-II-1966, S. K . Baker (1, BYUC) .

Color pattern unclear, possibly due to teneral condition. COSTA RICA: Alajuela: 20 km S Upala , 25–31 Oct. 1990, F . D. Parker (1, BYUC) ;

same data except 20 Jan.–12 Feb. 1991 (1, BYUC) ; same data except 10–29 May 1991 (1, BYUC); ca. 15 km SW Volcán Arenal, Arenal Vista Lodge , 13–15 Aug. 1995, J. E . Eger (1, TAMU). Guanacaste : 3 km SE R Naranjo , 14–20 Aug. 1993, F . D. Parker (1, BYUC). Heredia: Est. Biol. La Selva , 11–13 Jan. 1995, E. G . Riley (3, TAMU). PANAMA: Coclé: Cerro Gaital , 10–12 June 1985, E . Riley & D. Rider (1, EGRC). Colón: Coco Solo Ammo Area , 2-II-1976, H. E . Altman, UV light (1, BYUC); Pipeline Road, Gamboa , 22-VII-1972, Engleman (1, BYUC). Darién: P. N . Darién, Rancho Frío Station , 8.0198°N, 77.7322°W, 90 m, 1–9 June 2015, E. G . Riley (5, EGRC). Panamá: C29 Rd., 5 km E Gamboa, 27-VIII-1972 (2, BYUC); La Pita signal station rd., 8-VI-1976, E. G . Riley (1, EGRC); Madden Forest , 18-V-1980. E . Riley & D. LeDoux (1, EGRC); Madden Forest , 9°05′N, 79°35′W, 7-VII-1972, Engleman (1, BYUC); 5 mi. W Paraíso, 14-VIII-1971, W . Bivin (1, EGRC). Panamá Oeste: Cerro Campana , 18-III-1973, Strauch (1, BYUC) .

Geographic Distribution. This species occurs from Honduras to Peru. A report from the United States ( Kim et al. 2003) is surely in error.

Plant Associations. These insects feed on the foliage of Cecropia Loefl. ( Urticaceae ) ( Kirmse and Chaboo 2018).

Comments. Online images of type material are available for both C. atrocoerulea and M. nicaraguensis ( MCZ 2020) . Specimens with entirely pale elytra correspond to M. nicaraguensis , those with entirely dark elytra to C. atrocoerulea , and those with bicolored elytra to M. depressa . However, although these color forms are partially correlated with distribution, the ranges broadly overlap. Indeed, careful reading of the preceding Material Examined section will reveal that some localities have multiple color forms. Of note, the type locality of M. depressa (bicolored elytra) is likely in Colombia, even though most specimens with bicolored elytra are from Central America and most South American specimens have entirely dark elytra. Moreover, many specimens are intermediate between the main color forms. Additionally, there are no significant differences in genitalia. In view of these considerations, we prefer to treat the three names as strict synonyms.

Figures

Fig. 1. Platycesta depressa, form with entirely black elytra. A) Dorsal view, B) Lateral view, C) Ventral view, D) Pronotum.

Fig. 2. Platycesta depressa. A) Form with entirely pale elytra, dorsal view, B) Form with entirely pale elytra, ventral view, C) Form with bicolored elytra, dorsal view, D) Anterior view, E) Epipleuron.

Fig. 3. Platycesta depressa. A) Female, antenna, B) Female, distal abdominal ventrites, C) Male, distal abdominal ventrites.

Fig. 4. Platycesta depressa, female. A) Reproductive organs, B) Spermatheca, C) Vaginal palpi, D) Last visible tergite, E) Tignum, F) Abdominal ventrites, G) Last (internal) tergite.

Fig. 5. Platycesta depressa, male. A) Median lobe of aedeagus, dorsal view, B) Median lobe of aedeagus, lateral view, C) Median lobe of aedeagus, distal portion, D) Spiculum, E) Last visible tergite, F) Last (internal) tergite, G) Abdominal ventrites.

Fig. 6. Distribution of Platycesta depressa, form with entirely pale elytra.

Fig. 7. Distribution of Platycesta depressa, form with bicolored elytra and entirely black terminal ventrite.

Fig. 8. Distribution of Platycesta depressa, form with bicolored elytra and with only apex of terminal ventrite yellow or brown.

Fig. 9. Distribution of Platycesta depressa, form with bicolored elytra and with majority of terminal ventrite yellow or brown.

Fig. 10. Distribution of Platycesta depressa, form with entirely black elytra and with entirely pale terminal ventrite.