Eretmocerus aureus (Girault) comb. n.

Metanthemus aureus Girault, 1928: 4. Type data: AUSTRALIA: Queensland: Aratula, 17. v.1923, Girault, A.A., forest. Holotype, ♀. Type depository: QM. [examined].

Diagnosis

Antenna with clava 6.5× as long as broad; pedicel 4× as long as broad (Figure 12A). Fore wing nearly 3× as long as broad; parastigma (pst) curved (Figure 12B); submarginal vein with 3 dorsal setae; marginal vein with 3 setae; marginal fringe 0.5× fore wing width (Figure 12B). Mid tibial spur 0.3× as long as basitarsus (mbt) length (Figure 12C).

Material examined

Holotype: See above.

Comments

Metanthemus aureus Girault, 1928 was described in a private publication in the tribe Alaptini Perkins, 1912 (Mymaridae), a frequent classification used by Girault for species now recognised as in Cales Howard, 1907 and Eretmocerus (Girault, 1928). Girault compared Metanthemus with Paranthemus Girault, 1915, (= Cales) (Hayat 1983). However, he did not compare it with Eretmocerus itself, despite his previous valid description of Eretmocerus australis Girault, 1921. Metanthemus was later transferred to Aphelinidae by Huber (2005), but not assigned to a subfamily. Metanthemus has since remained a valid genus, known only from its short description in Girault (1928).

The sole specimen of Metanthemus aureus is mounted in Canada balsam under irregular shards of broken glass in a thick preparation (Figure 12D). Shards of glass are also mounted next to parts of the specimen, presumably to prevent compression of the specimen. Dahms (1983) indicated that this specimen is the holotype. The specimen clearly belongs to Eretmocerus based on the configuration of the antenna, tarsal formula (4-4-4), and other diagnostic characteristics typical of Eretmocerus. Eretmocerus aureus (Girault, 1928) is near to, or identical with, Eretmocerus mundus Mercet, 1931, except for a curved parastigma (Figure 12B, compare with De Barro et al. (2000, fig. 9)) and the relative proportions of the clava. Notably, the holotype of Eretmocerus aureus will key to Eretmocerus mundus in multiple identification keys (Hayat 1998; Zolnerowich and Rose 1998; De Barro et al. 2000), but with some difficulty due to the collapsed funicular segments of the type specimen. A more extensive redescription of Eretmocerus aureus is currently undesirable because many key features are not visible in the type specimen. Instead, photographs of the type specimen are provided for the first time (Figure 12). Girault (1928) mentions setal tracks on the fore wing disc, but discal setae are uniformly scattered, the typical character state for Eretmocerus (Figure 12B).

Most notably, Eretmocerus aureus differs from females of Eretmocerus mundus by the length of the clava (Figure 12A): 8–8.5× as long as broad. The clava of Eretmocerus mundus was described as less than 5× as long as broad (Hayat 1998), but De Barro et al. (2000) described it as 5.8–6.8× as long as broad, and Zolnerowich and Rose (1998) described it as 5.7–7.4× as long as broad. The number of setae on the mesoscutal midlobe (2 pairs) is also used to define Eretmocerus mundus (Hayat 1998). The condition of the type specimen of Eretmocerus aureus prevents a clear assessment of the setae on the midlobe of the mesoscutum.

Because of the poor visibility of morphological features on the only known specimen, Eretmocerus aureus is tentatively recognised as a separate species. Greater certainty would require an accurate count of setae on the midlobe of the mesoscutum, and examination of intact funicular segments. The relatively long antennal clava and the curved parastigma are the only defining features of Eretmocerus aureus that distinguish it from Eretmocerus mundus. Because of the importance of Eretmocerus mundus in the biological control of the Bemisia tabaci species complex, further research should prioritise the collection of specimens of Eretmocerus from the type locality of Eretmocerus aureus, and the comparison of morphological and molecular data from fresh specimens with those of other Eretmocerus. This is of even greater importance as the relative dimensions of the holotype are potentially inaccurate as it appears the specimen was allowed to collapse prior to being mounted. This synonymy was discovered independently by three of the current investigators but was not published until now.