Psephenopalpus browni Arce-Pérez, 2004

Psephenopalpus browni Arce-Pérez, 2004

Figs. 5–8 View FIGURES 1–8

Diagnosis. Adult male ( Figs. 5, 6 View FIGURES 1–8 ): body oval and tapered anteriorly. Head black, short, transversely with very prominent and spherical eyes.Antenna long, filiform subserrate. Maxillary palpus extremely long, second palpomere much longer than other palpomeres. Male genitalia. Trilobate, in dorsal view parameres broad, shorter than middle lobe with external margins sinuate distally, ending in rounded apex with lateral membrane ( Fig. 7 View FIGURES 1–8 ). In ventral view, penis longer than parameres, digitiform, widening at basal half with robust longitudinal, sublanceolate sclerite ( Fig. 8 View FIGURES 1–8 ).

Material examined. MEXICO: Chiapas: Cacahoatán, Ejido El Águila, cascada La Sirena , 15°06’08.8”N, 92°11’01.3”W, 1115 m, 06.xii.2018, Luna-Luna , Cancino-López , Almaraz-Hernández , Marquez-López , 1 male, D net ( CNIN); Cacahoatán, Ejido El Águila, cascada La Sirena, 15°05’37.0”N, 92°10’46.2”W, 1250 m, 24.iii.2022, Chacón-Hartleven, Chamé-Vázquez, 2 males, Surber sampler (ECO-TAP-E); same data except 21.iv.2022, 15 males, Surber sampler, 4 males, collected manually (ECO-TAP-E) GoogleMaps .

Geographical distribution. MEXICO, Chiapas (new state record) and Veracruz.

Habitat. The specimens from Ejido El Águila were collected from a wadable stream in the sub-basin Alto Cahoá, a tributary of the Cahoacán River, which drains areas with remnants of primary and secondary montane mesophyll forest. Most specimens were collected in riffles with Surber sampler, where water temperature was 18.73 °C (± 0.34 SD, standard deviation) and dissolved oxygen concentration was 13.41 mg /L (± 0.25 SD). In addition, a few specimens were collected manually on the periphyton of water-covered rocks. High habitat heterogeneity was observed, with an optimal condition of physical habitat (RBP = 0.90), including abundant riparian native vegetation with nearby coffee plantations (shade-grown coffee, Coffea sp. ). The stream had turbulent water flow, the elements of the channel were dominated by riffles and rapids zones (60% of total reach sampled), and composition of the inorganic substrate was dominated by cobbles and boulders (45% and 35% of reach sampled, respectively). Also, abundant allochthonous elements ( e.g., woody material and leaf packs) were observed in the stream channel.