Hydrochus debilis Sharp, 1882

Perkins, Philip D., 2020, Taxonomy of Guatemalan water beetles in the genus Hydrochus (Coleoptera: Hydrochidae), Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 291-301 : 293-295

Hydrochus debilis Sharp, 1882

( Figs 1 , 2 , 8 )

Hydrochus debilis Sharp, 1882: 89 .

Type material examined. LൾǤŦƟŦYPൾ (hereby designated, Fig. 8 ): male ( NHM): ‘ Hydrochus debilis Type D. S. Chontales. Nicaragua Janson // [male symbol] // LECTOTYPE [blue disc] // Chontales, Nicaragua. Janson. // B.C.A. Col. I. 2. Hydrochus debilis, Sharp. // HABITUS / GENIT. DIGITAL IMAGES captured 2020 P.D. Perkins // [red] LECTOTYPE Hydrochus debilis Sharp desig. P. D. Perkinsʼ. PARAĿൾǤŦƟŦYPൾ: female ( NHM): ‘ Hydrochus debilis Type D. S. Chontales. Nicaragua // [female symbol] // PARALECTOTYPE [blue disc] // Chontales, Nicaragua. Janson. // B.C.A. Col. I. 2. Hydrochus debilis, Sharp. // LECTOPARATYPE H.debilis by J. L. Hellman 75 // [yellow] PARALECTOTYPE Hydrochus debilis Sharp desig. P. D. Perkinsʼ.

Additonal material examined (15 spec.). GUATEMALA: Izabal, 1 mi. N. Morales.Km 239 Atlantic Hwy, 16–18.viii.1965, leg. Paul J. Spangler (1: NMNH); 20 mi. SW Puerto Barrios, 16.viii.1965, leg.Paul J. Spangler (4: NMNH); 28 mi. SW Puerto Barrios, 16.viii.1965, leg.Paul J. Spangler (1: NMNH); Rio Dulce Fy., 2.vii.1974, leg. W. E. Steiner (9: NMNH).

Lectotype designation. The NHM kindly provided two syntypes of Hydrochus debilis , which are part of the Sharp Biologia Centrali-Americana types collection. The syntypes consist of one male and one female. I have selected the male to serve as lectotype and labeled it as such, and provide images of the habitus, male genitalia, and labels of that specimen ( Figs 1 , 2 , 8 ). The other syntype has been labeled paralectotype. One additional specimen provided by the NHM as ‘Possible typeʼ is a different species, from Mexico. One of the syntypes bears a lectotype label, by J. L. Hellman, but this designation was never published. This label has been reversed and “unpub.” written on the reverse side.

Differential diagnosis. Among Guatemalan species, H. debilis is recognized by the combination of moderate size (ca. 2.69–3.08 mm), the densely punctate pronotum with deep foveae, and the elytral sculpture, each elytron having four raised interstriae: 3 rd slightly raised over basal ¼, 4 th raised in area anterior to large callus of 5 th, 5 th raised from about anterior ¼ to midlength, and usual callus of 5 th. The distinctive male genitalia ( Fig. 2 ; described below) are also diagnostic.

Redescription. Habitus as illustrated ( Fig. 2 ). Size (in mm): Lectotype: body (length to elytral apices / width) 2.88 / 1.04; head width 0.69; pronotum length / width 0.75 / 0.71; PA 0.67; PB 0.56; elytra length / width 1.85 / 1.04. Body size moderate (ca. 2.69–3.08 mm in Guatemalan specimens). Dorsum dark grey to black, with very slight if any iridescence, elytra with black spots. Legs dark brown, with tibiofemoral joints slightly darker. Punctation on elytra ca. 2–4× that of pronotum. Elytra interstriae ca. 0.5–1.0× strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Callus on 5 th in usual area, large, very strongly raised.

Pronotum length ca. equal width, widest at ca. anterior 1/3, narrowed at base, sides sinuate, minutely denticulate; anterior margin slightly bisinuate; depressions deep, reliefs sharply raised, depressions and reliefs densely punctate.

Elytra with spaces between strial punctures narrow ridges to ca. 0.5× their diameter; 3 rd interstria slightly raised over basal fourth; 4 th interstria raised in area anterior to callus of 5 th; 5 th interstria raised from about anterior fourth to midlength, raised area separated from callus of 5 th by very slight depression; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with moderate angulation.

Male genitalia ( Fig. 2 ). General characters: paramere tips moderately large, extending beyond distal tip of aedeagus, sagittate, distal ends pointed, lateral margins between plsa and distal end slightly emarginate, medial margins of tips very slightly arcuate toward midline and well separated from lateral margins of aedeagus; parameres in dorsal/ventral views constricted at base of tips and dorsally with low ridge; parameres in dorsal/ventral views much wider at widest point than tips; parameres in lateral view wide, sinuate, and tapering to sharp tips; aedeagus greatest width at adbl, shaft (portion of aedeagus distal to adbl) in dorsal/ventral views very narrow, almost parallel-sided; aedeagus dorsal margin sinuate in lateral view; basal piece shorter than parameres, with rim of orifice sclerotized.

Dorsal surface: adtl located at about distal fifth of aedeagus; pdmm very slightly narrowly overlapping alm at about midlength of aedeagus; adbl very large, much wider than paramere area lateral to adbl, distinctively shaped.

Ventral surface: pvmm overlapping alm at base; pwsa near base.

Figures

Fig. 1. Dorsal habitus of Guatemalan Hydrochus species.

Fig. 2. Hydrochus debilis Sharp, 1882, habitus and male genitalia of lectotype.

Fig. 8 Hydrochus lectotype labels.A – H. obscurus Sharp, 1882; B – H. debilis Sharp, 1882.