Morphometric analysis and taxonomic re-evaluation of Pepsis cerberus Lucas and P. elegans Lepeletier (Hymenoptera: Pompilidae: Pepsinae: Pepsini)

Abstract

Hurd (1952) separated Pepsis cerberus Lucas from P. elegans Lepeletier (Hymenoptera: Pompilidae: Pepsinae: Pepsini) based on external morphology and biogeography. Vardy (2005) synonymized the familiar and historically well-documented P. cerberus and P. elegans, combining these Nearctic taxa with several Neotropical variants in an extremely broad definition of P. menechma Lepeletier. In doing so, Vardy (2005) breached the principle of nomenclatural stability. He ignored the prevailing usage and clearly violated articles 23.2, 23.3 and 23.9.1.2 of the ICZN (1999). Morphological differences, ecological divergence, and narrow sympatric geographic distribution of P. cerberus and P. elegans contradict Vardy (2005) and justify full species status (Kurczewski 2023a). Furthermore, we propose the removal of the two species from the P.menechma list of synonyms and recommend full species reinstatement as Pepsis cerberus, restored status and Pepsis elegans, restored status. Pepsis menechma becomes a senior synonym of P. elegans. Morphometric re-examination and statistical analysis of P. cerberus and P. elegans structural features strongly support their reinstatement. Quantitative measurement of 10 parasitoid-related morphological characteristics of the females revealed the two species differ significantly in frons width/head width, head length/head width, vertex length/head width, vertex length/head length, flagellomere 1 length/flagellomere 1 width, forewing length/mesosoma width, and hind tibial inner spur length/hind basitarsus length. Pepsis cerberus and P. elegans females are structurally and statistically similar in gena-postgena corner radius, fore femur width/mesosoma width, and number of hind tibial serrations.