Psephenops Grouvelle, 1898

Chacón-Hartleven, Erick A., Luna-Luna, Alba Magali, Chamé-Vázquez, Eduardo R., Mejía-González, Gamaliel & Contreras-Ramos, Atilano, 2025, A new species of Psephenops Grouvelle, 1898, with new distribution data and habitat notes of the psephenine water-penny beetles from Mexico (Coleoptera: Psephenidae: Psepheninae), Zootaxa 5722 (1), pp. 79-94 : 92

Key to adult males of New World species of Psephenops Grouvelle

(Based on Arce-Pérez & Novelo-Gutiérrez 2017 and Barr & Shepard 2024; the species P. robacki (Spangler, 1966) , was not included in the key because only description of the female is available).

1. Pronotum with 3 small tuberculiform prominences; elytra with several longitudinal ridges on disc.............. grouvellei

- Pronotum without tuberculiform prominences; elytra without longitudinal ridges on disc............................. 2

2. Protibiae without apicolateral denticle; male genitalia as in figure 26...................................... prestone

- Protibiae with apicolateral denticle; male genitalia variously arranged............................................ 3

3. Tarsal lobes enlarged (lobe of tarsomere 2 covers ventrally the full-length of tarsomeres 3-4 and reaching at least 80% the length of tarsomere 5)....................................................................................... 4

- Tarsal lobes short (reaching the basal half or less of tarsomere 5)................................................ 5

4. Basal half of parameres, in dorsal view, separated by a deep cleft ( Fig. 32 )........................................ 7

- Basal half of parameres, in dorsal view, fused ( Fig. 37 )....................................................... 9

5. Parameres apically truncated ( Fig. 27 ); 4th maxillary palpomere at least twice as long as preceding palpomeres together smithi

- Parameres not apically truncated; 4th maxillary palpomere not as above.......................................... 6

6. Parameres strongly convergent on apical third, medial margins of parameres separated from each other by a narrow, drop-like cleft ( Fig. 28 ).................................................................................... lupita

- Parameres more or less parallel on apical third, medial margins of parameres separated from each other by a wide, U-shaped cleft ( Fig. 29 ).................................................................................. shepardi

7. Apex of parameres, in dorsal view, spine-like, widely divergent ( Fig. 30 )............................... spiniparameri

- Apex of parameres, in dorsal view, not spine-like, convergent ( Figs. 28, 29 )....................................... 8

8. Prosternal process flat, with apex lanceolate. Penis with a small, lateral tooth ( Fig. 31 )....................... mexicanus

- Prosternal process subcylindrical, with apex bifid. Penis lacking lateral projections ( Fig. 32 )...................... bifidus

9. Small individuals, length less than 2.4 mm; antennae moniliform-serrate; parameres truncate, with apex straight ( Fig. 33 )............................................................................................. panamaensis

- Large individuals, length greater than 2.5 mm; antennae not serrate; parameres not truncate......................... 10

10. Antennae long, filiform; fore- and middle legs with segments 1 and 2 lobulate, hind legs only with segment 1 lobulate ( Haiti)............................................................................................. haitianus

- Antennae short, moniliform; all legs with segments 1 and 2 lobulate............................................ 11

11. Elytra slightly striate.................................................................................. 12

- Elytra smooth....................................................................................... 14

12. Parameres in dorsal view widened on apical fifth, with apex rounded; penis slightly produced apically ( Fig. 34 ). maculicollis

- Parameres in dorsal view uniformly broad; penis not produced apically......................................... 13

13. Parameres in dorsal view short, with apices broadly but unevenly rounded; penis with apex semi-truncate ( Fig. 35 )...... trini

- Parameres in dorsal view elongate, apices evenly rounded; penis with apex rounded ( Fig. 36 )............... argentinensis

14. Parameres in dorsal view broadly separate, apex subtriangular; penis digitiform, with a basal, lateral, subtriangular projection from each side ( Fig. 37 )........................................................................ triangularis

- Parameres in dorsal view close to each other, apex rounded ( Fig. 38 ); penis acuminate apically ( Figs. 13, 14 ).. arcei , sp. nov.

Figures

FIGURES 26–38. Male genitalia of Psephenops spp., dorsal. 26) P. prestone; 27) P. smithi; 28) P. lupita; 29) P. shepardi; 30) P. spiniparameri; 31) P. mexicanus; 32) P. bifidus; 33) P. panamaensis; 34) P. maculicollis; 35) P. trini; 36) P. argentinensis; 37) P. triangularis; 38) P. arcei, sp. nov. Figs. 26 and 34 modified from Spangler (1990); Figs. 27 and 35 modified from Barr & Shepard (2024); Fig. 28 modified from Arce-Pérez (2002); Fig. 30 modified from Arce-Pérez & Novelo-Gutiérrez (2013); Fig. 31 modified from Arce-Pérez & Novelo-Gutiérrez (2000); Figs. 32 and 37 modified from Arce-Pérez & Novelo-Gutiérrez (2017); Fig. 36 modified from Déleve (1967).

FIGURES 9–15. Psephenops arcei, sp. nov., male holotype (dry specimen, genitalia glycerin). 9) body, dorsal; 10) body, ventral; 11) body, dorsolateral; 12) midleg tarsus, left; 13) genitalia, dorsal; 14) genitalia, ventral; 15) lateral, right.