Postembryonic development of Actinopus cf. insignis and Diplura paraguayensis (Araneae, Mygalomorphae)

GALIANO, MARÍA E.; GOLOBOFF, PABLO A.

BULLETIN - BRITISH ARACHNOLOGICAL SOCIETY

British Arachnological Society

Año: 1996 vol. 10 p. 121 - 126

0524-4994

The postembryonic development of two mygalomorphspiders, Actinopus cf. insignis (Actinopodidae) and Dipluraparaguayensis (Dipluridae), is studied. The first postembryonic instar is intrachorional, covered by the embryoniccuticle with egg teeth. In both species the second instar hasa strongly bent body, integumentary spicules, few hairs onthe tarsi, a pair of simple tarsal claws, and anterior andposterior spinnerets. The cheliceral fang of A. cf. insignis hasa false pincer, while that of D. paraguayensis has onlysubapical denticles. The third instar A. cf. insignis retains sixspinnerets (all of them with spigots); the anterior lateralspinnerets are lost in later stages. Three tarsal claws arepresent, and the paired claws are toothed. The paired clawsof third instar D. paraguayensis have a single, sinuous rowof teeth (adults have two rows); the inferior claw is toothed.The presence of six spinnerets, monoserially dentate pairedclaws, and pectinate inferior claws in early instars suggeststhat a reversal to these plesiomorphic states in a relatedtaxon, Micromygale, could be due to neoteny and not to ade novo origin.