Psephenus palpalis Champion, 1913

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 : 86-88

Psephenus palpalis Champion, 1913

Figs. 20–23

Diagnosis. Adult male ( Figs. 20, 21 ): body oblong-ovate, rather broad, depressed, dorsum shining, densely pubescent. Head profusely rugulose, vertex foveate, dorsal concavity not divided. Elytra oblong, little wider than thorax; pronotal sides strongly convergent anteriorly, apex not more than half as wide as base. Maxillary palp threequarters length of antenna, second segment of maxillary palp usually longer than third and fourth combined. Male genitalia ( Figs. 22, 23 ): apex of median penial spicule enlarged and bluntly rounded.

Material examined. MEXICO: Chiapas: Cacahoatán, Ejido Ahuacatlán ( 15°02’20.4”N, 92°10’15.6”W), 680 m, 22.iii.22, Chacón-Hartleven, Chamé-Vázquez , 1 male, D net (ECO-TAP-E) ; Pichucalco, Tectuapan, 17°28’47.74”N, 93°07’21.32”W, 66 m, 8.iii.2024, Chacón-Hartleven, 3 males, Surber sampler (ECO-TAP- E); same data except 01.iv.2024, 1 male (ECO-TAP-E) ; same data except 30.iv.2024, 2 males (ECO-TAP-E) ; Pichucalco, Tectuapan, 17°26’13.30”N, 93°09’31.76”W, 99 m, 29.iv.2024, 2 males (ECO-TAP-E); Pichucalco, sitio experimental del INIFAP, 17°33’30.9”N, 93°03’26.2”W, 54 m, 29.v.24, 1 male (ECO-TAP-E); Guerrero: Cacahuamilpa, Río Dos Bocas , 1.iv.1984, Vázquez, Villa, 1 male ( CNIN) ; R[uta] 1[3]4 Altamirano-Zihuatanejo Km 102, 22-vi-1990, 1300 m, Bueno, Barrera, 1 male ( CNIN) ; Morelos: Amacuzac, Río Chalma (ojo de agua), 25.iii.1984, Vázquez, 1 male ( CNIN) ; Tlaltizapán, Balneario Ejidal Sta. Isabel, 150 m, 16.iv.1997, Bueno, Barba, Rojas, González, 1 male ( CNIN) ; Oaxaca, Teotitlán, Río Xiquila , 5.v.1988, Cervantes, 2 males ( CNIN) ; San Juan Bautista Cuicatlán, (Santiago) Dominguillo, río Las Huertas , 12.vi.1996, Barba, Rojas, 1 male ( CNIN) ; Puebla: Telpatlán, 3.x.1988, Cervantes, 1 male ( CNIN) ; Tabasco: Huimanguillo, Villa G [uadalu]pe 2da. Secc., arroyo Las Flores, Carr [etera] Malpasito-Carlos A. Madrazo 5.92 km, 17°22’30.0”N 93°36’15.0”W, 12.vi.1997, Bueno, Barba , 1 male ( CNIN) ; Veracruz: Los Tuxtlas, Río Máquinas , 14.vii.1979, Bueno, 1 male ( CNIN) ; Los Tuxtlas, Balzapote, 5.v.1981, Hernández, Ortega, 2 males ( CNIN) , Santiago, 1 male ( CNIN) ; same data except 14.v.1984, Rodríguez, 2 males ( CNIN) ; Los Tuxtlas, río La Palma , 18.vi.1996, Alatorre-Castillo, 1 male ( CNIN) ; Los Tuxtlas, río Máquinas, 18°37’16”N, 95°05’26.6”W, 21 m, 29.iv.2016, Contreras-Ramos , 2 males, D-net ( CNIN) .

Geographical distribution. MEXICO, Chiapas (new state record), Estado de México, Guerrero (new state record), Hidalgo, Morelos, Oaxaca (new state record), Puebla (new state record), Tabasco (new state record), and Veracruz (new state record) ( Fig. 25 ).

Habitat. The specimen from Ahuacatlán, Chiapas was collected from emergent macrophytes at the riparian zone of a wadable stream of the sub-basin Bajo Cahuá, a tributary of the Cahoacán River. The stream drains agricultural areas, with sun coffee plantations ( Coffea sp. ) and exotic eucalypt trees ( Eucalyptus sp. ) along the riparian zone. The specimen came from riffles, where water temperature was 21.93 °C (± 0.63 SD) and the dissolved oxygen concentration was 13.68 mg /L (± 0.78 SD). The stream had a good physical habitat condition (RBP = 0.66) with turbulent water flow, channel elements were dominated by riffles and rapids (60% of reach sampled), and inorganic substrate was dominated by pebbles and gravel (35% and 30% of reach sampled, respectively). The specimens from Tectuapan, Chiapas were collected in fast-flowing zones of wadable streams of the Pichucalco River sub-basin, tributaries of the Grijalva River. Six specimens came from riffles of a stream that drains areas with mixed land uses, including primary-secondary forests and cultivated pastures, where water temperature was 28.68 °C (± 3.75 SD) and dissolved oxygen concentration was 4.55 mg /L (± 0.27 SD). Two specimens were found in riffles of a stream that drains areas of secondary forest, where water temperature was 30.42 °C (± 0.62 SD) and dissolved oxygen concentration was 7.05 mg /L (± 0.51 SD). One specimen was found in riffles of a stream that drains areas of primary forest with abundant riparian vegetation and pristine conditions, where the water temperature was 28.65 °C (± 0.35 SD) and dissolved oxygen concentration was 6.61 mg /L (± 0.29 SD). The stream had a physical habitat condition ranging from good to excellent (RBP = 0.70, 0.75 and 0.95, respectively), channel elements were dominated by riffles and rapids (50-60% of reach sampled), and inorganic substrates were dominated by pebbles (50% and 60% of reach sampled) and cobbles (70% of reach sampled), respectively.

Figures

FIGURES 16–23. Adult males, habitus (dry specimens) and genitalia (glycerin). 16) Psephenops shepardi, body dorsal; 17) P. shepardi, body ventral; 18) P. shepardi, genitalia dorsal; 19) P. shepardi, genitalia ventral; 20) Psephenus palpalis, body dorsal; 21) P. palpalis, body ventral; 22) P. palpalis, genitalia dorsal; 23) P. palpalis, genitalia ventral.

FIGURES 24–25. Updated distribution maps of the thirteen species of psephenids (Psephenidae: Psepheninae) known to occur in Mexico.