UTILITA DI NUOVI CARATTERI NELLA SISTEMATICA DEL GENERE AGATHIDIUM PANZER (COLEOPTERA, LEIODIDAE) E LORO IMPIEGO NELLA DESIGNAZIONE DI DUE SINONIMI

Abstract

Taxonomic and systematic research on Agathidium underlies to severa! problems. because of the big number of species and the frequent intraspecific variability of features, even in male copulatory organ. Furthermore, many originai species descriptions are inadeguate and mistakes in specific identification are recognizable in many Collections.

In order to introduce new diagnostic characters, the authors do a morphological survey of:

• -  The Hamann's organ. Within the Agathidium it generally consists of only two particular sensilla (fig. 1), one in both IX and X antennomeres (we find three sensilla only in A. nigripenne: the third one is in the VII antennomere). Each sensillum is made with a periarticular gutter (s), which can possess l or 2 variably shaped vesicles (v); otherwise the gutter is lacking in vesicles. For number and shape the latter are identic in IX and X antennomeres of an unic individuai and constant within the species, without sex differences .

• -  Spermatheca. lt is a Iittle capsule with thiçk and well sclerotized walls. Its shape is very

UTILITY OF NEW CHARACTERS IN SYSTEMATIC OF GENUS Agathidium PANZER

(Coleoptera, Leiodidae) AND THEIR USE IN DESIGNATING TWO SYNONYMS

Viene esaminato in generale il comportamento morfologico dell'organo di HAMANN delle antenne, della spermateca e del meso e metatorace nel genere Agathidium. Lo studio delle variazioni di tali organi a livello specifico viene pro- posto quale mezzo per risolvere particolari problemi tassonomici e sistematici. Come esempio di applicazione, viene fatta la revisione di cinque specie di Aga- thidium, comunemente ritenute valide e ben distinte: A. badium Er., A. bicolor Sahlb., A. escorialense Bris., A. opuntiae Reitt. e A. pisanum Bris. Dall'esame di esemplari di serie tipica e dal confronto fra le caratteristiche classiche e quelle degli organi in oggetto si conclude che le specie valide sono tre soltanto. Vengono designate le conseguenti sinonimie (A. bicolor Sahlb. = A. pisanum Bris., A. opun- tiae Reitt. = A. badium Er.) e rifatte le descrizioni delle tre specie rimanenti.

variable within the genus, but relatively constant in each species. A basal part and an

apical part are recognizable (pb and pa).
- Meso and metathoracic sterna. They underlie to remarkable variations, probably linked

to the Agathidium behaviour « to form into a bali». On mesosternum we recognize (fig. 6) a middle carina (cm) and two latera[ lines (ll); on metasternum (fig. 7) two femoral lines (fl). In the opinion of authors, the primitive situation is characterized (fig. 6.A) by latera! lines joined to each other (mesosternum subdivided in two parts, A and P), middle carina and femoral lines absent: a similar situation we find in species of dose related genera (Anisotoma, Amphycillis and Liodopria) and of Leiodini tribe. On the contrary, other features look peculiar of Agathidium: lateral lines shortened or absent, middle carina more or less in relief or secondarily absent, femoral lines present (in- complete or extended to margines of metasternum), metasternum shortened.

On the basis of a direct examination of type specimens, the authors have clone the revision of five species: Agathidium badium, A. bicolor, A. escorialense, A. pisanum and A. opuntiae. The use of new diagnostic characters was necessary because of the variability of microsculpture, punctation, aedeagus apex shape, etc.

Hamann's organ and mesosternum allow to separate A. escorialense (figs. 9 and 10). Then, two patterns of spermatheca are recognized in the specimens attributable to the other four species: a) the first pattern (fig. 11.C) with apical part short and increased towards apex in pisanum-bicolor; b) the second pattern with apical part slender and narrowed towards apex (fig. ll.B) in badium-opuntiae.

These new data allow to designate the following synonymies: Agathidium bicolor Sahl. 1880 = Agathidium pisanum Bris. 1872 Agathidium opuntiae Reitt. 1885 = Agathidium badium Er. 1848

A new description of the three surviving species is given.