Aleochara (Maseochara)

Introduction

This subgenus comprises 14 species that occur in Neotropical and southwestern Nearctic, and in the Ethiopian and Oriental Regions. It includes the largest species of the Aleocharini and probably the largest in the subfamily Aleocharinae.

Characteristics

The species of the subgenus Maseochara are characterized by: conspicuous transversely meshed microsculpture of the forebody; body narrow, elongate and subparallel and more or less flattened; and mesosternum not carinate. Body size of the species ranges between 2.3 and 13.0 mm (from KLIMASZEWSKI 1984 and KLIMASZEWSKI & JANSEN 1994). A. (M.) valida (body length 7.0-13.0 mm) is the largest Aleochara species.

Identification Guides

The Nearctic species have been revised by KLIMASZEWSKI (1984), the African ones by KLIMASZEWSKI & JANSEN (1994). KLIMASZEWSKI (1987) included two South American species.

Bionomics

Maseochara species appear to be associated with rotting plant material. Some American species live in decaying cacti (KLIMASZEWSKI 1984, KLIMASZEWSKI & JANSEN 1994). A. (M.) valida is the only species whose development has been investigated. Its host is Volucella marginata (Diptera: Syrphidae). The third instar larva leaves the host puparium for pupation (COQUILLETT 1891).

Discussion of Phylogenetic Relationships

KLIMASZEWSKI & JANSEN (1994) proposed three (or four) main evolutionary lineages of Maseochara, the American, the African and the Oriental lineages (the oriental species possibly represent two separate lineages). The American lineage is characterized by the flattened body, distinct regular hexagonal microsculpture and more or less sparse pubescence of the forebody. Within the American fauna, KLIMASZEWSKI (1984, 1987) and KLIMASZEWSKI & JANSEN (1994) recognized three species groups (valida, duplicata and wickhami groups), of which the latter two are monotypic. The wickhami group is distinguished by the flat hexagonal sculpticells of the microsculpture and the more glossy and sparsely pubescent pronotum. The duplicata and valida groups have a microsculpture of very convex sculpticells and a dull and densely pubescent pronotum. The duplicata group is characterized by the mid and hind tibiae which bear long, protruding setae in the apical third, and by male and female sexual characteristics. Since no autapomorphies are given for the valida group, its monophyly is uncertain. Within the valida group, A. (M.) opacella and A. (M.) gracilis are very closely related (KLIMASZEWSKI 1987). The African lineage is distinct by the less flattened body and the irregularly meshed microsculpture on the forebody that consists of micropunctures forming irregular ridges. This lineage is divided into the angusticollis and the brunneipennis groups, which are each characterized by genitalic features. The hypothesis that the main lineages are monophyletic is based on biogeography (from KLIMASZEWSKI 1984, 1987 and KLIMASZEWSKI & JANSEN 1994).

It is uncertain that Maseochara is monophyletic. The main characteristic (distinct microsculpture of the forebody) is also found in other subgenera (e.g. Emplenota, Polystomota, Coprochara partially). Consequently, it is doubtful that this microsculpture is an autapomorphy of this group, especially since there are different types of microsculpture in Maseochara (KLIMASZEWSKI & JANSEN 1994). The other characteristics of Maseochara given by KLIMASZEWSKI (1984) and KLIMASZEWSKI & JANSEN (1994) are also not likely to be autapomorphies. The monophyly of the main evolutionary lineages is not well established as well, since KLIMASZEWSKI & JANSEN 1994 did not provide information about which states of distinctive characteristics are apomorphic, and which are plesiomorphic.

References

Coquillett, D. 1891. Another parasitic Rove Beetle. U.S. Div. Insect Life 3: 318-319

Klimaszewski, J. 1984. A revision of the genus Aleochara Gravenhorst of America north of Mexico (Coleoptera: Staphylinidae, Aleocharinae). Mem. Ent. Soc. Canada 129: 1-211

Klimaszewski, J. 1987. A review of Sharp's types of Aleochara from Latin America (Coleoptera: Staphylinidae). Ent. Scand. 20: 1-14

Klimaszewski, J. & R. Jansen 1994. Systematics, biology and distribution of Aleochara Gravenhorst. Part 4: subgenus Maseochara Sharp in the Afrotropical region. J. Afr. Zool. 108: 163-180

Maus, Christian and Ashe, James S. 1998. Aleochara (Emplenota). Version 11 September 1998 (under construction). http://tolweb.org/Aleochara_%28Emplenota%29/9904/1998.09.11 in The Tree of Life Web Project, http://tolweb.org/