A MINUTE FUNGUS BEETLE LARVA (COLEOPTERA: CORYLOPHIDAE) FROM DOMINICAN AMBER: A STRIKING EXAMPLE OF MORPHOLOGICAL CONVERGENCE
We describe and illustrate the first fossil larval corylophid and highlight its striking resemblance to other onisciform insect larvae. Larva characteristics are as follows: broadly ovate, strongly flattened, 2.3 mm long, 1.6 mm wide, and unicolorous dark brown dorsally. All surfaces are heavily sclerotized with notal surfaces ornamented with six thoracic and nine abdominal lobes (8-9 not fused). All lobes distinctly separated, lacking gills, A9 tergum simple, and lacking urogomphi. The head prognathous subparalellepipedal, short, wider than long, concealed from above by broadly rounded first pronotal lobe; with relatively long, well-developed antennae, probably bearing three segments (second about 50-60% total length), ending in, at least, 3-4 setae, and the apicalmost the strongest and longest; antennae slightly longer than thorax (ratio 11:9); antennae much longer than head width (ratio 5:3); apical fourth of antennae visible from above under anterior pronotal lobe. All legs are well-developed, moderately separated, articulated at base, with simple tarsungulus (leg 3 with 5 segments), basal portion of thoracic lobes maculated of dark brown and yellow. Head plus thorax is about half the length of larva. Thoracic and abdominal lateral lobes bear about ten strong, and well-separated slightly clavate-ornamented setae of various lengths.
The extreme onisciform morphology is common to a wide variety of immature terrestrial and aquatic insects, including: Termitaphididae (Heteroptera), Coccoidea (Homoptera), Psephenidae, Discolomidae, some hispine Chrysomelidae (Coleoptera), and the Platypezidae (Diptera). Although there are significant differences in their bauplane, this phenomenon represents a striking example of convergence.