Ascidicolidae Thorell 1859

Family Ascidicolidae Thorell, 1859

Diagnosis (female). Body cylindrical. Prosome 5-segmented, consisting of cephalosome and 4-segmented metasome. Urosome 5- or 6-segmented, with 3- or 4-segmented abdomen. Fifth pedigerous somite obscurely defined. Caudal rami usually small, armed with 5 or 6 setae. Rostrum not developed. Antennule small, 5- to 8-segmented; aesthetascs small. Antenna consisting of coxobasis and 2-segmented endopod, or 4-segmented including obscurely defined coxa, basis bearing 1 spine distally; distinct flexure present between basis and first endopodal segment; second endopodal segment bearing terminal claw. Labrum broad, bearing 1 or 2 dentiform processes at posterolateral corners. Mandible consisting of coxa and palp; coxa with well-developed gnathobase bearing irregular denticles on medial margin; palp uniramous, or biramous with well-defined basis, exopod and endopod. Maxillule consisting of precoxa and palp; precoxa bearing 7 to 9 setal elements on arthrite; palp uniramous or biramous; coxal endite present or absent. Maxilla 2- to 4-segmented; syncoxa (first segment) with 2 endites each bearing 1 seta, or 1 endite bearing 2 or 3 setae, or endites absent; basis with strong claw in addition to setae, or with setae only; endopod reduced, 1- or 2-segmented; in Ascẚdẚcçla and Styelẚcçla basis and endopod completely fused to form allobasis. Maxilliped unsegmented and unarmed, or armed with 1 to 7 setae. Legs 1-4 broad, biramous; coxa usually lacking inner seta; basis of leg 1 with or without inner distal spine; exopods 2-segmented; endopods mostly 2-segmented. First endopodal segment of legs 1 and 2 always lacking inner seta. Exopods and endopods of legs 1-4 usually armed with spines only. Leg 5 large, lamellate, bearing rudimentary setae, or consisting of lamellate protopod bearing outer distal seta and setiferous exopod. Leg 6 represented by 3 dentiform processes on genital operculum.

Remarks. Thorell (1859) first established the Ascidicolinae as a subfamily of the family Notodelphyidae in order to accommodate his new genus Ascẚdẚcçla Thorell, 1859. As highlighted by Illg & Dudley (1980), it was treated both as a subfamily and as a family level taxon throughout the late nineteenth and the twentieth centuries. Its composition has varied over this period but it gradually expanded until it contained a total of seven main component taxa, each of which was recognized as a subfamily of the family Ascidicolidae by Illg & Dudley (1980) in their comprehensive revision. The seven subfamilies were: the Ascidicolinae, Buprorinae Thorell, 1859, Botryllophylinae Sars, 1921, Enterocolinae Della Valle, 1883, Enterognathinae Illg & Dudley, 1980, Enteropsinae Aurivillius, 1885, and Haplostominae Chatton & Harant, 1924. The Enterognathidae was treated as a separate family by Boxshall & Halsey (2004) and Ohtsuka et al. (2010), and comprises associates of echinoderm and hemichordate hosts. It is not considered further here. Subsequent revision of the remaining six subfamilies resulted in the recognition of four valid family level taxa (see Boxshall & Halsey, 2004).

Illg & Dudley (1980) retained only two genera, Ascẚdẚcçla and Styelẚcçla Lützen, 1968, in their subfamily Ascidicolinae which was subsequently returned to family status, as the Ascidicolidae by Boxshall & Halsey (2004). Two new genera eamẚstyelẚcçla gen. nov. and Bathycçpçla gen. nov. are added to the family in the present work. All species currently placed in this family were found living in association with solitary ascidians.

In the genera Styelẚcçla, eamẚstyelẚcçla gen. nov. and Bathycçpçla gen. nov., leg 5 consists of a lamellate protopod and a small, setiferous distal segment. This distal segment was recognized as the endopod by Lützen (1968) and by Illg & Dudley (1980), but Boxshall & Halsey (2004) re-interpreted it as representing the exopod. The four genera of the Ascidicolidae are distinguishable using the following key.