Psephenoidinae, Bollow, 1938

Shepard, William D. & Sites, Robert W., 2019, Larval Psephenidae (Coleoptera: Byrrhoidea) of Thailand: Annotated List and Illustrated Key to Genera, The Coleopterists Bulletin 73 (2), pp. 259-282 : 273

Subfamily Psephenoidinae

Larvae of this small subfamily have gills housed in a chamber on the ninth abdominal sternum and covered by a ventral operculum. Unlike larvae in Eubriinae , those of this subfamily have the last one or two abdominal segments encircled by paratergites of the previous abdominal segment(s) ( Fig. 12 ). Individuals are much smaller than other psephenids. Larvae , pupae ( Fig. 24 ), and adults regularly occur underwater on stones and wood. Adults commonly come to lights at night. Larvae of this subfamily are difficult to identify to the genus level because they are either undescribed or only incompletely described. Only larvae of Sinopsephenoides ( Fig. 38 ) can be accurately identified. Thus, all other larvae mentioned below are identified only to the subfamily level, although known from Thailand in the adult stage. However, different larval types ( Figs. 39–40 ) can be distinguished. Distributions are provided in Maps E–F .

Figures

Figs. 10–14. Morphological structures. 10) Schinostethus: Gills concealed beneath ventral operculum; 11) Undescribed Eubrianacinae: Palmate gills exposed on venter; 12) Psephenoidinae: Ninth abdominal segment surrounded by paratergites of eighth abdominal segment; 13) Schinostethus: Ninth abdominal segment not surrounded by paratergites of eighth abdominal segment; 14) Mataeopsephus: Gills with branches arising from central stalk. 7 = seventh abdominal segment; 8 = eighth abdominal segment; 9 = ninth abdominal segment.

Figs. 21–24. Morphological structures. 21) Dicranopselaphus: Prothoracic paratergites extending from middle of lateral margins (from Lee et al. 2007); 22) Undescribed Eubrianacinae: Unique pronotal suture (yellow arrow) configuration; 23) Schinostethus: Pupa; 24) Psephenoidinae: Pupa.

Figs. 37–40. Psepheninae and Psephenoidinae genera, dorsal habitus. 37) Mataeopsephus; 38) Sinopsephenoides;