Agathidium Panzer

Genus Agathidium Panzer

Agathidium Panzer, 1797: no. 13. Type species: Tetratoma globosa Herbst [1792] (= Silpha seminulum Linnaeus [1758], syn. in ?? [already by Gyllenhal 1810: 573] (by monotypy). Note: Proposed as nomen protectum by provision of ICZN 1999: Art. 23.9 (Wheeler & Miller, 2005: 34).

= Volvoxis Kugelann, 1794: 535 (not preoccupied by Volvox Linnaeus [1758], Chlorophyta). Type species: Tetratoma globosa Herbst (= Silpha seminulum Linnaeus [1758] by subsequent designation of Newton, 1998: 95 (10 species in original description). Note: Proposed as nomen oblitum by provision of ICZN 1999: Art. 23.9 (Wheeler & Miller, 2005: 34) due to lack of use as a valid name after 1899.

= Agathidium Illiger, 1798: 81 (unnecessary replacement name for Volvoxis Kugelann [1794] (in part), incorrectly assumed to be preoccupied by Volvox Linnaeus [1758]). Type species: Tetratoma globosa Herbst [1792] (= Silpha seminulum Linnaeus [1785]), fixed by autotypy as replacement name for Volvoxis. Note: It is not clear if Illiger intended to propose a new generic name here; he did not refer the generic name to Panzer (1797), although he did refer to Panzer’s (1797: 13) species treatment of Agathidium globosum. The above treatment assumes it was an intentional proposal of a new name to replace Volvoxis.

Note 1: Volvoxis Kugelann has priority for the name of this genus, but this name was rejected and replaced with Agathidium by Illiger (1798) in the mistaken belief that Volvoxis was preoccupied by Volvox Linnaeus, and this replacement name became generally accepted. However, Panzer (1797) had already used Agathidium in the same sense a year earlier, without explanation. Illiger (1798) made no mention of Panzer’s (1797) use of Agathidium so these have often been treated as independent names (e.g., Newton, 1998: 95 – 96), with Panzer’s name having priority and Illiger’s name being a junior homonym of it. All three names have the same type species as indicated above, and thus are objective synonyms. Wheeler & Miller (2005: 34) cited Article 23.9 of the Code (ICZN, 1999) to set aside priority and accept Agathidium Panzer as the valid name for the genus (nomen protectum) and treat Volvoxis as a forgotten name (nomen oblitum). Agathidium has been attributed to both Panzer and Illiger at various times, sometimes (by accident) even in the same publication (see Newton, 1998: 94, 95), but Panzer, 1797 is correct.

Note 2: Revised in Hlisnikovský (1964a) and Miller & Wheeler (2005b) and Wheeler & Miller (2005).

Note 3: Wheeler & Miller (2005) abandoned the use of subgenera and proposed a system of species groups, as used below, which may have some relationship to previously established subgenera. Most Mexican and Central American species are in the oniscoides species group. The rich species diversity of Mexico and Central America is obviously only partly known.

Key: to species groups in Wheeler & Miller, 2005: 37.

Distribution: 822 spp.—Holarctic, Africa, Oriental, northern Neotropical.

Note 4— Species wrongly reported for the Neotropics:

A. exiguum Melsheimer [1844] —The record of A. californicum Horn [1880] [= A. exiguum, Miller & Wheel- er, 2005b: 156 syn] for Guatemala (Quiché Mts., 7000 – 9000 ft.) in Matthews, 1887: 75 is a misidentification

of an unknown different species (Miller & Wheeler, 2005b: 160).

A. oniscoides Palisot de Beauvois [1805] —The record of Matthews, 1887: 74 for Mexico (Jacala, Hidalgo State) is in error (a misidentification, in Miller & Wheeler, 2005b: 151).

Biology: Usually in forested habitats and on slime molds (Hatch, 1957; Russell, 1979; Newton, 1984; Wheeler, 1987, 1990).