Proboscis ornamentation as a diagnostic character for the Anoplodactylus californicus-digitatus complex (Arthropoda: Pycnogonida) with an example from the Anoplodactylus eroticus female

Abstract

Females of the Indo-Pacific species Anoplodactylus eroticus (Arthropoda: Pycnogonida: Phoxichilidiidae) are described for the first time. The presence of peculiar ventral outgrowths or protuberances on the female proboscis of A. eroticus and 13 other Anoplodactylus species motivates an evaluation of a californicus-digitatus complex, based on external morphology and species distribution. The anatomy and development of proboscis protuberances is assessed using scanning electron microscopy (SEM), Nomarski optics, and flourescence microscopy. External morphology of A. eroticus is compared to that of apparently related species. An identification key for the 14 species of Anoplodactylus with females bearing a proboscis with ventral protuberances is provided here as an identification tool.