Pleistodontes, SAUNDERS, 1882

Lopez-Vaamonde, Carlos, Dixon, Dale J., Cook, James M. & Rasplus, Jean-Yves, 2002, Revision of the Australian species of Pleistodontes (Hymenoptera: Agaonidae) fig-pollinating wasps and their host-plant associations, Zoological Journal of the Linnean Society 136 (4), pp. 637-683 : 640-641

GENUS PLEISTODONTES SAUNDERS, 1882

Pleistodontes Saunders, 1882: 164 and 1883: 8–10. Type species: Pleistodontes imperialis Saunders by monotypy.

Plistodontes Schulz, 1906: 148 . Unnecessary emendation.

Neoceratosolens Girault, 1915b: 312 . Type species Neoceratosolens nitens Girault by original designation. Synonymy by Hill (1967b: 92).

Proceratosolens Girault, 1933: 3 . Type species Proceratosolens medionigra Girault : by monotypy. Synonymy by Hill (1967b: 92).

Diagnosis

The genus Pleistodontes is rather difficult to define despite a relatively homogeneous morphology. The female head is elongate, mostly longer than wide (but in some species as long as wide, e.g. Pleistodontes mandibularis Wiebes from Papua New Guinea), bearing three ocelli on the vertex. The head is fully chitinized without a membranous area above the toruli; at most, P. greenwoodi and Pleistodontes xanthocephalus sp. nov. exhibit a V-shaped membranous line on the median line of the head. Eyes usually shorter than the genae but as long as the genae in some species. Mandibular appendage elongate, usually bearing more than 20 transverse laminae, rarely less (11–13 in P. rigisamos ), sometimes bearing transverse rows of small teeth (e.g. P. regalis , P. nitens , P. froggatti ). Antennal scape usually elongate (at least 2–3 ¥ as long as broad), sometimes shorter, mostly bearing a dorsal lamina which can be curved outwards and downwards. Pedicel rather short without dorsal spines. Third antennal segment elongates into a triangular process, always undivided and frequently elongate. Some species have no triangular expansion on the third antennal segment (First funicular segment, F1). Antenna bear one or two rows of sensilla linearia. Mesosoma bears pollen pockets, sometimes reduced, or absent (all Papuan species and one Australian species). Venation is always complete. The fore tibia usually bears 2–3 spines in the dorso-apical comb, rarely only one, and four in one Papuan species ( Pleistodontes immaturus Wiebes ). Apical spiracles small, rarely surrounded by large concave peritremata ( P. nitens ). Ovipositor sheaths about as long as or shorter than metasoma (all Australian species), but can be up to twice the length of the metasoma in some Papuan species.

In most species, the antenna has three transverse or (sub)quadrate segments between the pedicel and the two-segmented club. One Papuan species ( Pleistodontes blandus Wiebes ) has two segments. All male tarsi are pentamerous. Usually, the mesoscutum is separated from the mesonotum. It is fused in one Papuan species ( P. blandus ). The metanotum is fused to the propodeum, at least partly. In one species ( P. froggatti ) the metanotum is separated from the propodeum.

Diversity

Pleistodontes contains 25 valid species (17 in Australia), including the seven species described as new in this paper. However, there are almost certainly further species to be described, especially from Papua New Guinea. In our opinion Pleistodontes claviger ( Mayr, 1885) , collected in the botanical garden of Bogor (Java) from syconia of Ficus elastica Roxb. ex Hornem. , does not belong to Pleistodontes . While F. elastica is a species closely related to the Urostigma sect. Malvanthera, both from a morphological (K. Berg and D.J. Dixon, pers. comm.) and a molecular point of view (E. Jousselin, pers. comm.), its supposed pollinator is clearly not in the genus Pleistodontes .

In the absence of type material, several morphological features, described by Mayr (1885) and Grandi

(1928b), enable us to exclude P. claviger from

Pleistodontes :

(i) The third antennal segment is subdivided into two parts (see Grandi, 1928b: fig. VIII-1, p. 127) but is entire in all Pleistodontes species.

(ii) The roundish shape of the pedicel and the massive shape of the scape are unknown features in Pleistodontes .

(iii) The mandibular appendage is very short, bearing 7–8 transverse lamellae (see Grandi, 1928b: fig. VIII-2, p. 127), unlike any known Pleistodontes species. P. rigisamos , the species with the shortest appendage, bears 11–13 lamellae, but all other species have between 15 and 80 lamellae (an average of about 30).

(iv) The mandible has one distinct apical tooth and bears about six ventral ridges, a combination not exhibited by other species of Pleistodontes .

(v) All known species of Pleistodontes , except P. claviger , bear sensilla linearia (non elongate multiporous plate sensilla).

In fact, only two morphological characters are at all consistent with a classification into Pleistodontes : (1)

the pentamerous tarsi of the males, although several

Waterstoniella males also have pentamerous tarsi; (2)

the complete fusion of the mesonotum, metanotum and propodeum of the males ( Grandi, 1928b: fig. IX-3,

p. 129), which is an aberrant feature in Pleistodontes ,

shown only by P. blandus .

Clearly, further collections of B. claviger are needed to confirm its taxonomic position and host association.

The host plant, F. elastica , is a widespread species,

introduced by humans as an ornamental throughout the tropics and may have been colonized successfully by a different pollinator species in Java, as has been reported for Ficus lutea Vahl in Africa ( Compton,

1990).

Biology

Where the host Ficus of a Pleistodontes species is known, it always belongs to the Urostigma sect. Malvanthera. All species develop in the syconia and pollinate, either actively or passively, their host plant. Most of the pollinator species are species-specific with their host fig; however, there are a few exceptions to this one-to-one rule (see Discussion). Nothing is known of the immature stages of Pleistodontes .

Distribution

The genus is restricted to Australia, New Guinea and adjacent islands. Ficus obliqua G. Forst. , and probably its pollinator, has a slightly wider natural distribution, reaching New Caledonia. Furthermore, Ficus macrophylla and Ficus rubiginosa Desf. ex Vent. and their pollinators have been introduced to several different countries ( Israel, New Zealand and USA).

Comments

Following Rasplus et al. (1998) we consider the family Agaonidae to comprise solely the pollinating wasps of Ficus . All the nonpollinating fig wasps belong to other Chalcidoid families. Supposedly, females of subfamily Agaoninae have mandibular appendages with many transverse combs of teeth, whereas the females of subfamily Blastophaginae have only a few transverse lamellae. However, this is problematic with Pleistodontes , since both forms of appendage are found in the genus (in contrast to other Australasian genera of Agaonidae , which can all be placed in Blastophaginae ). For this reason, Boucek (1988) questioned the validity of Pleistodontes ; however, it now seems more likely that the current subfamilial classification is wrong since molecular studies strongly support the monophyly of Pleistodontes ( Lopez-Vaamonde et al., 2001) but contradict the integrity of the two subfamilies ( Machado et al., 2001). Clearly, Agaonidae needs a thorough phylogenetic analysis to better determine the intrafamilial classification.