Compactopediina

Introduction

The subtribe Compactopediina is comprised of 4 genera. Three of these contain only a single species and are inquilines in the nests of the termite Longipeditermes longipes (Nasutitermitidae) in southest Asia. Members of Compactopedia Kistner are known from Sarawak and Malaya, while those of Emersonilla Kistner and Hirsitilla Kistner are both known only from Sarawak (Kistner 1970b). Kistner (1982) transferred the genus Discoxenus Wasmann from the tribe Termitodiscini to the subtribe Compactopediina (See CHARACTERISTICS). He also described 3 new species for a total of 7 species in the genus. The species of Discoxenus are known from Burma, Ceylon, Malaysia and India, and all are obligate inhabitants of the nests of Odontotermes (Nasutitermitidae).

Kistner (1970b) misspelled the name of this tribe as the "Compactopedina" in his original description. Newton and Thayer (1992) corrected the spelling to "Compactopediina."

Characteristics

Members of the subtribe Compactopediina are distinguished from all other members of the Aleocharini by the combination of: compact limuloid or sublimuloid body form, broad shield-shaped pronotum that partially or fully covers the head in dorsal aspect; the "trilobed" (Kistner 1970b) abdominal tergum IX; and their occurrence in the nests of Longipeditermes longipes and Odontotermes termites. Kistner (1982) includes the genus Discoxenus within this subtribe despite its tarsal formula 4-4-5, which is very unusual among the Aleocharini. Kistner (1970b) states that the shape of abdominal tergum IX is unique to this subtribe. However, he (Kistner 1970a) also describes a "trilobed" abdominal segment IX as characteristic of the subtribe Hodoxenina. Kistner (1970, 1982) provides habitus photographs of a member of each genus and illustrations of diagnositic features for all genera and species in the subtribe.

Bionomics and Evolution of Host Relationships

The species of Discoxenus are found exclusively in the fungus gardens of some (but not all) species of Odontotermes in the Indo-Malayan region. They have not been found in Odontotermes nests from Africa, though such nests have been examined for termitophiles (Kistner 1982). Kistner (1982) observed specimens of Discoxenus malaysiensis in petri dishes with workers, nymphs and soldiers of their host termite. He found that the beetles mingled freely with the termites and did not show any "furtive or evasive behavior"(p. 183). The nymphs and workers palpated the beetles, most often on the abdomen, less frequently on the pronotum. The beetles also palpated the soldiers but were ignored by these termites. Kistner (1982) provides photographs of beetles interacting with the host termites. Bionomics of the species associated with Longipeditermes longipes have not been studied.

Kistner (1982) proposes that the plesiotypic pattern of host relationship within the Compactopediina is association with Longipeditermes longipes, and association of Discoxenus with Odontotermes represents a relatively recent host transfer. The alternative, that the pattern of host relationships in the Compactopediina represents host tracking from the time that the Nasutiterminae (Longipeditermes) and Macrotermitinae (Odontotermes) diverged, is less parsimonious in the context of the reconstructed phylogeny.

Discussion of Phylogenetic Relationships

Phylogenetic relationships among the 4 genera in the Compactopediina are provided by Kistner (1982). Kistner (1970b) believed that Compactopedia and Emersonilla are more closely related to each other than either is to Hirsitilla. However, he did not explicitly give the characteristics shared by these taxa that led him to that conclusion. In 1982 he provided a phylogenetic analysis based on 29 morphological characteristics, using Aleochara tristis as closest outgroup and Termitohospes punctulatus (a representative of the tribe Termitohospitini which Kistner believed to be related to the Aleocharini) and Zyras (Lomechusini) as more distant outgroups. He found that the Compactopediina are monophyletic based on: mesonotum reduced to 1/2 length of metasternum, mesonotum about 1/3 length of metanotum and abdominal segment VII with 2 pairs of paratergites (not fused). This latter feature is widespread in the Aleocharinae and is probably plesiomorphic for the lineage. Within the Compactopediina Hirsitilla is the most basal lineage. Emersonilla, Compactopedia and Discoxenus are hypothesized to be monophyletic based on 3 characters: antenna fusiform with antennomere petioles completely covered; gula relatively long; abdominal segments III, IV,V approximately equal in width. These last two characters are derived in parallel elsewhere on the tree, are widespread in the Aleocharinae, and are likely to be plesiomorphic in the context of the aleocharines as a whole. Compactopedia and Discoxenus are hypothesized to form a monophyletic group based on 2 unique characters: mesonotum 1/2 length of metanotum; abdominal tergum VII with 2 pair of paratergites fused posteriorly.

Other Names for Compactopediina

• Compactopedina

References

Kistner, D. H. 1970a. New termitophilous Staphylinidae from Hodotermitidae (Isoptera) nests. Jour. New York Entomol. Soc. 78: 2-16.

Kistner, D. H. 1970b. New termitophiles associated with Longipeditermes longipes (Haviland) II. The genera Compactopedia, Emersonilla, Hirsitilla, and Limulodilla. Jour. New York Entomol. Soc. 78: 17-32.

Kistner, D. H. 1982. A revision of the termitophilous genus Discoxenus with a study of the relationships of the genus and notes on its behavior (Coleoptera, Staphylinidae). Sociobiology 7(2): 165-186.

Newton, A. F., Jr. and M. K. Thayer. 1992. Current classification and Family-Group names in Staphyliniformia (Coleoptera). Fieldiana:Zoology, new series No. 67: 1-92.