Psychopomporus Jean, Telles, and Miller

Jean, April, Telles, Nicole D., Gibson, J. Randy, Foley, Dan & Miller, Kelly B., 2012, Description of a New Genus and Species of Stygobiontic Diving Beetle, Psychopomporus felipiJean, Telles, and Miller (Coleoptera: Dytiscidae: Hydroporinae), from the Edwards-Trinity Aquifer System of Texas, USA, The Coleopterists Bulletin 66 (2), pp. 105-110 : 106

Psychopomporus Jean, Telles, and Miller , new genus

( Figs. 1–4, 6–7 )

Type Species. Psychopomporus felipi new species.

Diagnosis. Adults of Psychopomporus are distinct among Hydroporinae based on the combination of the following character states: 1) adaptations to subterranean environment including light pigmentation, fused elytra, and metathoracic wings and compound eyes reduced ( Fig. 1 ); 2) prosternal process strongly declivous, apically reaching the anterio- medial projection of the metasternum ( Figs. 2, 3 ) and with a prominent projection anteriorly ( Fig. 3 ); 3) mesotibia apically expanded and strongly arcuate medially ( Fig. 2 ); and 4) elytral epipleuron broad and flat anteriorly ( Fig. 2 ). The general body form and obvious cave adaptations are similar to other stygobiontic members of Dytiscidae , suggestive of convergent adaption to the subterranean environment. Many stygobiontic diving beetles have a shortened prosternal process that does not reach the anterior margin of the metasternum and a distinct habitus with the pronotum cordate and a strong discontinuity in the curvature between the pronotum and elytron. These features are not present in Psychopomporus ( Figs. 1–3 ).

Etymology. The genus is named Psychopomporus (masculine), from the Greek psychopompos, meaning “guide of souls” and –porus, a common root for genus names in the subfamily Hydroporinae .

Distribution. Specimens of the single species in this genus were recovered in the flow from two springs discharging into the western side of San Felipe Creek (29.37234°N, 100.88602°W) in Del Rio, Val Verde County, Texas, USA ( Fig. 7 ). These springs discharge from the Edwards-Trinity aquifer system. The distribution of P. felipi throughout this aquifer, as well as possible occurrence in other aquifers, is unknown.

Discussion. Psychopomporus belongs within the tribe Hydroporini (Hydroporinae) based on the following characters: 1) pronotum lacking bilateral basal plicae ( Fig. 1 ); 2) scutellum not externally visible ( Fig. 1 ); 3) pro- and mesotarsi moderately pseudotetramerous, though not strongly so ( Fig. 2 ); 4) prosternal process strongly declivous ( Figs. 2, 3 ); 5) apices of elytra evenly rounded ( Figs. 1, 2 ); 6) posterior margin of metacoxal processes in similar plane as abdominal sternum ( Fig. 2 ); 7) metacoxal process with lobes small but distinct, covering the base of the metatrochanter ( Fig. 2 ); 8) metatarsal claws of equal length ( Fig. 2 ); 9) male genitalia bilaterally symmetrical ( Fig. 4 ); and 10) male lateral lobe with a single segment ( Fig. 6 ). Based on morphology alone, relationships of Psychopomporus to other Hydroporini (and relationships among Hydroporini taxa in general) are not clear and a comprehensive analysis of this group using morphology and molecular data are needed for placing this unusual taxon. Such an analysis is currently under way with preliminary results suggesting that Psychopomporus is, indeed, a valid genus (K. Miller, personal observation).

Figures

Figs. 1–6. Psychopomporus felipi. 1) Dorsal habitus; 2) Ventral habitus; 3) Prosternal process, left lateral aspect, arrow points at medial prosternal prominences; 4) Male median lobe, ventral aspect; 5) Male median lobe, right lateral aspect; 6) Male right lateral lobe, right lateral aspect. Scale bar = 1 mm for Figs. 1–3 only.

Fig. 7. Distribution of Psychopomporus felipi and other Texas subterranean diving beetles, showing extent of Edwards-Trinity Aquifer.