Caccothryptus abboti

Caccothryptus abboti 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 in 1953 by Harry George Champion in Haldwani, India alongside an earlier 1925 specimen collected nearby. Like the other Caccothryptus species described by Matsumoto, it was distinguished from its original classification of C. testudo due to differences in the shape of its genitalia. One specimen collected by Champion was identified as the holotype for C. abboti and named for English radio presenter Nick Abbot.

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 1953 by forester Harry George Champion in the Haldwani division of the Kumaon Himalayas, India. These were labeled as C. ripicola and C. testudo, species which Champion had previously described in 1923. These were stored at the British Natural History Museum. In 2021, Natural History Museum entomologist Keita Matsumoto identified a number of distinct species from these specimens. One male specimen was labeled as the holotype of Caccothryptus abboti. C. abboti was placed in the species group C. compactus and named for English radio presenter Nick Abbot.

Description
The Caccothryptus abboti specimen has an elytral length of 3.21 mm, and an elytral width of 2.62 mm. Its prothorax measured 1.01 mm in length and 2.05 mm in width. C. abboti 's body is enlongated oval, dark brown spare for reddish-brown tibia and patches of long setae, yellow along the underside and white on the dorsum. 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 specimens, beyond a longer fifth abdominal ventrite on the female.

The beetle's genitals display a number of differences from the original classification of C. ripicola, which enabled its classification as a separate species. C. abboti 's aedeagus is long and highly sclerotised. It has an asymmetric apex on the median lobe. Their parameres are deeply curved along the top and slightly curve downwards from a side view. Between the parameres is a deep depression forming a rounded U-shape.