Hydrophilus (Dibolocelus) nucleoensis Arce-Pérez & Arriaga-Varela, 2021

Arce-Pérez, Roberto, Arriaga-Varela, Emmanuel, Novelo-Gutiérrez, Rodolfo & Navarrete-Heredia, José L., 2021, Giant water scavenger beetles Hydrophilus subgenus Dibolocelus (Coleoptera Hydrophilidae) from Mexico with description of two new species, Zootaxa 5027 (3), pp. 387-407 : 394-395

Hydrophilus (Dibolocelus) nucleoensis Arce-Pérez & Arriaga-Varela sp. nov.

Figs. 5, 6 ; 15–18 , 42

Etymology. This new species is named H. (D.) nucleoensis because of its distribution on the Central American Nucleus, a natural area formed by mountain ranges that go from the center-south of the state of Chiapas in Mexico to the north of Nicaragua (see Halffter 1987; Halffter & Morrone 2017).

Type material ( 31 ♂, 28♀). Holotype male: MEXICO: Chiapas: Reserva Montes Azules [16°50′00″N 91°30′00″O], 14.vii.1989, F. Arias y R. Barba cols. 1♂ ( CNIN). Paratipos mismos datos que el holotipo 6♂, 4♀ ( CNIN); Ocosingo, Corozal, [16°49′16″N 90°53′25″O], 100 msnm 23.v.1984, E. Barrera y A. Ibarra cols. 5 ♂, 4 ♀ ( CNIN), Ocosingo, Boca Lacantún, 29.v.1984 [16º34′ 50′′ N, - 90º 42′ 50′′O] 200 msnm, E. Barrera y A. Ibarra cols. 2 ♂, 2♀ ( CNIN); 24.v.1984, E. Barrera, A. Ibarra y M. Garcia cols. 1 ♂, 1♀ ( CNIN); 24.v.1984, A. Ibarra col. 1♂, 2♀ ( CNIN); Villa Flores, Villa Flores, [16°14′00″N 93°16′09″O], 500 msnm, 26.iv.1983, R. Fernández col. 1 ♂, 4.x.1983, E. Ríos col. 1 ♂, 19.x.1983, J. Melchor 1 ♀, 8.xi.1983, S. Serrano col. 1 ♀, 13.xi.1983, C. A. col. 1 ♀, 3vii.1990, G. Morales col. 1 ♂, 20.x.1999, Benjamin C. col. 1♀, Copainala, Copainala, 17° 06′ norte, 93° 17′ Oeste, 440 msnm, 16.v.1997, Arroyo, C. I. Sánchez col. 1 ♀ ( IEXA); Palenque, 19.v.1984, [17°30′33″N 91°58′56″O], 60 msnm, A. Ibarra y M. García cols. 1 ♀ ( CNIN); Palenque Malla Bell, 20.iv.1988, J. Kemner col. 1 ♀ ( IEXA), Acacoyagua, Acacoyagua, [15°21′00″N 92°41′00″O], 277 msnm, i.1999, N. Jimenez col. 1 ♀ ( IEXA), Mapastepec, Mapastepec, Rva. La Encrucijada, Laguna Chantutu, 28.viii,2000, 50 msnm, 15° 25′ 59″ Norte, 92° 53′ 52″ Oeste C. R. Chamé col. 1 ♀ ( IEXA). Campeche: Calakmul-Xpuhil [18°30′20″N 89°23′50″O], 29.v.2004, L. Cervantes y C. Mayorga cols. 1♂, 1♀ ( IEXA), Calakmul-Xpuhil, 200 msnm, 15/ 17.xi.2001, E. Barrera y H. Brailovsky cols. 1♀ ( CNIN); Calakmul, 24.vii.2014, Selva Alta Perenifolia, Fernando Escobar col. 1 ♂ ( IEXA); Guerrero: Hwy 200, 5 mi. S. Tecpan, 17°11.2′N, 100 36.7′′ W, 30 m, 20.vi.2010, D.Brzoska 1 ♂ ( SEMC). GUATEMALA. Escuintla: San José, [13°55′32″N 90°49′28″O], 4.i.1984, R. Pérez col. 2 ♂; Escuintla, Río San José, 9.vi.1985, E. Pérez col. 1 ♂ ( UVGC); Petén, San José, October 1991, leg. Frisch, 1 ♂ ( SEMC). NICARAGUA: Rio San Juan: Los Guatusos, río Pepaturro , [10°48′02″N 84°12′39″O], 21/ 29.v.2000, B. Hernandez y J. Sunyer cols. 2 ♂; Río San Juan, Sarapiqui, 1/ 5.ix.2006, A. Borges y P. Andino cols. 1 ♀; San Juan, San Carlos, 20.ii.1995, F. Collantes col. 1 ♀ ( IEXA). COS- TA RICA: Guanacaste Prov., Nandayure, nr. Carmona, 10°03′32.9′′N, 85°14′58.9′′W, 30 m, 15.i.2003, pond, leg. Short, Roughley , & Porras 1 ♂, 1♀ ( SEMC, INBio); Guanacaste Prov , Rd to Palo Verde , roadside ditch, 11.i2004, leg. Short & Lebbin,AS-04-027, 1 ♂ ( SEMC); Limon Prov. , Sector Cedrales de la Rita , 3 km N. Del Puente Rio Suerte , RutaPuerto Lindo , November 1995, leg. E. Rojas , INBIO-CRI002-378269 , 1 ♂ ( INBio).

Diagnosis. This species can be distinguished by the following combination of characters: Maxillary palpi clearly long and slender; fifth protarsomere as long as the basal ones together, flattened, with evident internal laminar expansion. This species is very similar to H. (D.) ovatus and H. (D.) pseudovatus sp. nov. but can be distinguished from them by [the characters the characters of H. (D.) ovatus and H. (D.) pseudovatus are provided in brackets for comparative purposes] the maxillary palpi clearly longer and slender, width of the third pal- pomere 0.065 ( Fig. 15 ) [ H. (D.) ovatus and H. (D.) pseudovatus sp. nov. present maxillary palpi with the third palpomere flattened and widened, with width greater than 0.080 mm (Figs. 7,11)], fifth protarsomere flat and with evident internal laminar expansion ( Fig. 16 ) [without or with slight internal laminar expansion ( Figs. 8, 12 )], abdominal ventrites 3 and 4 with slender glabrous area at midline ( Fig. 17 ) [ventrites 3 and 4 with wide glabrous area at mid-line ( Figs. 9, 13 )], abdominal ventrites 3 and 4 raised and slightly acute above at midline ( Fig. 17 ) [ab- dominal ventrites 3 and 4 raised and flat above at midline ( Figs. 9, 13 )]; H. (D.) ovatus and H. (D.) pseudovatus are mainly distributed in the Neartic portion of Mexico while H. (D.) nucleoensis sp. nov. is mainly distributed in the Neotropical part of Mexico, extending towards Central America in Guatemala and Nicaragua (Fig. 42).

Description male holotype. Body elongated-fusiform, length 32–37 mm (male holotype: 36 mm), width 17.0– 17.5 mm at humeri (holotype: 17.0 mm), 2.1× longer than wide, dorsally strongly convex and glabrous, ventrally flat and pubescent; dorsal color black with dark green hue; ventrally black with reddish hue, ventral vestiture pale yellow; antennae, palpi and legs black with reddish hue ( Figs 5, 6 ).

Head: Antennae short with nine antennomeres, scape large and robust, longer than the next four antennomeres together, pedicel subequal to the following three antennomeres, sixth antennomere long and oval, subequal to the previous four together, not covering the first article of antennal club ( Fig. 15 ). Maxillary palpi long and slender, with four palpomeres, with lengths: 4.0, 3.1, 2.8, 1.6 mm; first palpomere small, sub-conical, second long, curved, slightly broadened towards apex, third shorter and wider, slightly flattened towards apex, with 0.060 mm in its wider side, fourth short, oval, with truncated apex. Mentum hexagonal, 1.7× wider at base than long, lateral margins parallel at basal half, apically converging straightly, apex truncated and straight. Labial palpi short, length of palpomeres: 0.02, 0.09, 0.06 mm; first palpomere very small and subconical, second long and slightly broadened towards apex, 1.2× longer than the third, with short golden setae near the internal margin, third palpomere short and oval, with apex rounded ( Fig. 15 ).

Thorax: Prosternal lobes raised and apically rounded, with short reddish-yellow setae at apex; mesoventrite with broad keel, with lateral margins rounded and convergent towards apex, with a broad and shallow concavity at basal half, deeper towards apex. Metaventrite with keel wide and flat, with feeble median longitudinal groove, ending as a long spine reaching half-length of the second abdominal ventrite ( Fig. 6 ). Each elytron with two well-marked rows of black spots, one sublateral starting after the humerus, and other more incomplete on the sides ( Fig. 5 ).

Legs: Anterior tibiae with two spurs; internal one shortest, flat, sub-rectangular with apex truncate straight; external spur longer, sub-triangular, acute; fifth protarsomere as long as the basal ones together, flattened, with evident internal laminar expansion; tarsal claws curved, without basal tooth, internal claw slightly longer than external one, protarsomeres 2–5 with tufts of golden setae in the external margin ( Fig. 16 ).

Abdomen: Vestiture leaving a long oval glabrous area at mid-line in ventrites 3–4; and a broader sub-rectangular one in ventrite 5. Ventrites 3 and 4 raised and slightly acute above, with apex slightly rounded and projected on the next ventrites. ( Figs 6 , 17 ); ventrite 5 raised and slightly sharp above.

Genitalia: Total length 6.05 mm; phallobase long (length: 2.85 mm, width 2.25 mm) narrow with apex of manubrium rounded; parameres long (length: 4.25 mm), distinctly broadened at basal 3/5, elongated-oval at apical 2/5, with a deep oval concavity not reaching the apex, with minute teeth in the internal margin at the apical half, getting more abundant apically. Median lobe slightly shorter than the parameres (3.75 mm), broad sub-triangular, with a median sulcus, apex rounded ( Fig. 18 a, b ).

Sexual dimorphism. Females similar to males but with narrow maxillary palpi, anterior tibiae with long subtriangular spurs, tarsal claws curved and acute, with and basal acute tooth.

Variation. Body length between 32–37 mm, width 17.0– 17.5 mm, 1.8–2.0× longer than wide; body color can be dark brown with yellow-reddish hue (in old specimens); average length of maxillary palpomeres: 4.0, 3.0, 2.9 and 1.6 mm; average width of third maxillary palpomere: 0.65 mm; total length of labial palp: 1.8 mm.

Distribution. Mexico: Campeche, Chiapas, Guatemala: Escuintla and Nicaragua: Río San Juan (Fig. 42).

Figures

FIGURES 1–6. Dorsal and ventral view of Hydrophilus (Dibolocelus) spp. 1–2 H. (D.) ovatus Gemminger & Harold; 3–4 H. (D.) pseudovatus sp. nov.; 5–6 H. (D.) nucleoensis sp. nov.

FIGURES 7–18. Morphological structures and male genitalia of Hydrophilus (Dibolocelus) spp. 7-10 H. (D.) ovatus Gemminger & Harold; 7 ventral view of head (arrow: third labial palpomere); 8 protibia and tarsi, 9 ventral view of abdomen; 10a aedeagus ventral; 10b aedeagus dorsal; 11–14 H. (D.) pseudovatus sp. nov.; 11 ventral view of head(arrow: third labial palpomere); 12 protibia and tarsi, 13 ventral view of abdomen; 14a aedeagus ventral; 14b aedeagus dorsal; 15–18 H. (D.) nucleoensis sp. nov.; 15 ventral view of head (arrow: third labial palpomere); 16 protibia and tarsi, 17 ventral view of abdomen; 18a aedeagus ventral; 18b aedeagus dorsal.