Caradiophyodus

Caradiophyodus is an extinct genus of minute wasps in the superfamily Platygastroidea within the order Hymenoptera. The genus was described in 2023 by George Poinar Jr. and Fernando E. Vega and placed in the monotypic family Caradiophyodidae and is represented by a single species, Caradiophyodus saradae.^[1] The fossil was found in mid-Cretaceous Burmese amber from northern Myanmar and represents one of the earliest known records of platygastroid wasps.^[1]

The holotype specimen, a female, was recovered from amber deposits in the Noije Bum Summit Site, Hukawng Valley, Kachin State, Myanmar (26°20′N, 96°36′E). The amber has been dated to about 100 million years ago (late Albian to earliest Cenomanian), based on zircon U–Pb radiometric dating.^[1] The resin was produced by an Agathis-like conifer (family Araucariaceae) that formed part of a tropical coastal rainforest ecosystem. The amber likely originated in forests fringing estuarine or shallow-marine environments and was later redeposited in coastal sediments.

The holotype female measures about 1.3 mm long, excluding antennae. It has a compact platygastroid body form and a sessile abdomen. The head is hypognathous, about 210 µm long and 277 µm wide, with adjacent antennal sockets (toruli) above the oral cavity and stalked ommatidia. The antennae are 0.7 mm long and 15-segmented, a plesiomorphic (ancestral) character shared only with Proterosceliopsis plurima of the extinct family Proterosceliopsidae.^[1]

A distinctive horizontal cleft crosses the head between the eyes and subocular sclerites, bordered by a raised horseshoe-shaped sclerite; these are features unknown in any other platygastroid wasp. The mesosoma is smooth and non-metallic, with the pronotum extending to the tegula but lacking a pronotal carina. Wing venation is reduced: the forewing bears a small pterostigma and a submarginal vein reaching the wing margin, with no closed cells. The hind wing is narrow and lacks hamuli and an anal lobe. The metasoma has six visible segments plus a partly exposed seventh segment containing a telescoping ovipositor.

Caradiophyodus was likely a parasitoid, like other platygastroid wasps. A male scale insect (Hemiptera: Coccomorpha) preserved near the specimen suggests that its host may have been eggs or nymphs of scale insects, similar to the host associations of modern encyrtid wasps such as Anagyrus.^[1] Enlarged structures attached to the antennae, possibly representing plant secretions or host remains, have also been noted, although their nature is uncertain.