Family AMMOTHEIDAE Dohrn, 1881

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Family AMMOTHEIDAE Dohrn, 1881

Acheliidae Hayward, P.J. & Ryland, J.S. (eds) 1990. The Marine Fauna of the British Isles and North-West Europe. Volume 1. Introduction and Protozoans to Arthropods. Oxford : Oxford University Press.

Introduction

Ammotheidae have been shown recently to be a non-monophyletic group (Arango 2002; Arango & Wheeler 2007; Nakamura et al. 2007). Traditionally, all pycnogonid genera with atrophied or missing chelae, long palps and ovigers in both sexes, were grouped under Ammotheidae. Recent phylogenetic analyses, however, have shown that Ascorhynchus and Eurycyde, traditionally ammotheid genera, form a separate grouping, totally unrelated to Ammothella, Ammothea, Cilunculus, Tanystylum and Achelia, which are representative ammotheid genera forming a monophyletic clade (Arango & Wheeler 2007). A main characteristic separating Ascorhynchus and Eurycyde from their original family is the presence of multiple rows of oviger spines. Other less common genera are still to be included in further phylogenetic analyses to test their position in the Ammotheidae. These include Hemichela, Austroraptus, Paranymphon and Scipiolus, among other non-Australian genera.

Ammothea hilgendorfi (syn. Lecytorhynchus) has been used for studies on the arthropod brain (Strausfeld 1998), and recently the mitochondrial genome of Achelia bituberculata was published (Park et al. 2007).

Diagnosis

(Diagnosis for adults only) Most heterogeneous family. Tiny to quite large in size. Chelifores present, scape one or 2-segmented, some with full chelae, atrophied chelae, chelae lacking, sometimes chelifores lacking; palps 5-10 segmented; ovigers in both sexes, larger in males, 9 or 10-segmented, without functional strigilis. Cement gland outlets dorsal on femur. Eight legs only.