Caccothryptus brendelli

Caccothryptus brendelli is a species of minute marsh-loving beetle in the subfamily Limnichinae. The species was described alongside five other Caccothryptus species by Natural History Museum entomologist Keita Matsumoto in 2021, using specimens gathered by Martin J. D. Brendell (curator of the Coleoptera Department of Entomology at the Natural History Museum, London) at Kathmandu, Nepal in 1983. One of Brendell's specimens were distinguished from Caccothryptus testudo due to distinct genital structures and labeled C. brendelli after Brendell.

Taxonomy
The Limnichidae (minute marsh-loving beetle) genus Caccothryptus was first described by David Sharp in 1902. In 2014, the genus was divided into five species groups by Carles Hernando and Ignacio Ribera.

A group of Caccothryptus specimens were collected in 1983 in Kathmandu, Nepal by Martin J. D. Brendell, curator of Coleoptera Department of Entomology at the Natural History Museum, London. These were stored at the Natural History Museum. In 2021, museum entomologist Keita Matsumoto identified a number of distinct species from these specimens. One male specimen from Kathmandu, found under the bark of a dead tree, was labeled as the holotype for Caccothryptus brendelli. C. brendelli was placed in the species group C. testudo and named for Brendell.

Description
The Caccothryptus brendelli specimens identified by Matsumoto has an elytral length of 3.36 mm, and an elytral width of 2.44 mm. Their prothorax is 0.94 mm in length and 2.07 mm in width. C. brendelli has an elongated oval body, brown in colour except for reddish-brown tibia and long, white setae, on the dorsum and light yellow setae on the underside. Its tarsi are divided into five segments, of increasing length, with the fifth segment as long as the others combined. It has long, narrow, light brown tarsal claws. The beetle's head, smooth and punctured, is slightly retracted into its pronotum, and features eleven-segment antennae. Little sexual dimorphism exists between the male and female specimen, beyond a longer fifth abdominal ventrite on the female.

The beetle's genitals display a number of differences from the original classification of C. testudo, which enabled its classification as a separate species. The apex of C. brendelli 's median lobe narrows to a slightly pointed tip along the side. It has a narrow depression between the notches on the tip of the genitalia, both of which are V-shaped from below. The genitals' dorsum are wavy, forming two concave curves along the side.