Morionidius

Introduction

Five species distributed in the Oriental region. No key to species exists. Individuals have been found in rotten logs and at lights.

Characteristics

Small to medium sized, deep-bodied species readily recognized from all other morionines by the transverse sulci on the abdominal ventrites.

Morionidius and Stereostoma share the expanded apical labial palpomeres and have a significant number of shared characteristics of other morionines. Morionidius has features of the head and eyes that are intermediate between those found in Stereostoma and other morionines. The eyes in Morionidius species are very prominent, like Stereostoma, but have prominent tempora as in other morionines, which is lacking in Stereostoma. The labrum is also intermediate in form, very slightly emarginate, not straight as in Stereostoma nor deeply emarginate as in Morion. Morionidius lacks the prominently developed latero-apical spine of the protibia, which is very large in all other morionines. The transverse sulci of the abdominal ventrites in Morionidius is not found in any other morionine taxa but is known in various other pterostichine-grade taxa.

The female reproductive structures of Morionidius species are quite different and probably derived relative to those of other morionine taxa. The notched gonocoxite-2 is likely a synapomorphy for the genus. Notched gonocoxites and a sclerotized spermatheca is also found in species of Tshitsherinella Semenov (Chaetodactylini). Both of these taxa also have securiform labial papli and sulcate abdominal ventrites. Chaetodactylines are known to be parasites of scarab beetles (Jeannel 1948) and it is possible that Morionidius also has a parasitic life-style that led to the independent acquisition of these features.