Polyankyliidae, Ho and Kim, 1997

Kim, Il-Hoi, 2014, Six new species of Copepoda (Clausiidae, Pseudanthessiidae, Polyankyliidae) associated with polychaetes from Korea, Journal of Species Research 3 (2), pp. 95-122 : 119-121

Genera recognized in the Polyankyliidae

While establishing the genus Terebelliphilus to incorporate a new species Terebelliphilus simplex, Kim (2001a) placed this genus in the Sabelliphilidae . Terebelliphilus is here transferred to the Polyankyliidae . It carries a number of morphological features sharing with the type genus of the family, Polyankylis , as follows: (1) the antennule is six-segmented, with a reduced number of setae on proximal segments; (2) the antenna has a claw on the second endopodal segment and three claws on the terminal endopodal segment; (3) the labrum has prominent posterior lobes; (4) the mandible has a short, strongly tapering blade; (5) the maxilla has a short distal lash bearing few teeth and a large medial seta (seta I); (6) legs 1-3 have 2-segmented endopods; (7) leg 4 lacks an endopod; and (8) the male maxilliped has two massive, transformed setae on the second segment. Terebelliphilus simplex was found as a associate of the terebelliphilid polychaete Terebella ehrenbergi Grube from an intertidal mudflat in the Yellow Sea.

The genera Octophiophora Stock, 1988 and Stockia Sebastian and Pillai, 1974 are here transferred also to the Polyankyliidae . Octophiophora was originally placed in the Nereicolidae ( Stock, 1988) , but Boxshall and Halsey (2004) removed it to Octophiophora -group, along with Stockia . Octophiophora lacertae Stock, 1988 , the only species of the genus, was discovered from a vial contained various serpulid polychaetes collected in the Great Barrier Reef. Octophiophora has a vermiform body, peculiarly bearing four pairs of long lateral processes on the trunk. Nevertheless, it has several characteristic features sharing with Polyankylis and Terebelliphilus , as follows: (1) the antennule is reduced in segmentation and setation (five-segmented, with three setae on the first segment); (2) the antenna has a claw and two setae on the second endopodal segment and three claws in addition to setae on the terminal endopodal segment; (3) the mandible has a spinulose secondary blade on the concave medial margin, as in Polyankylis orientalis ; (4) the basis of the maxilla has a large medial seta (seta I) and few teeth on the distal lash; (5) the maxilliped has a pair of large setae on the basis (second segment) and a long spiniform claw and a large seta on the endopod (terminal segment), as in Polyankylis orientalis and P. ovilaxa n. sp.; and (6) legs 1-4 lack an inner coxal seta, as in Terebelliphilus , and their endopods are reduced (in legs 1-3) or absent (in leg 4).

Stockia was originally recorded as a genus of the Clausiidae by the original describers ( Sebastian and Pillai, 1974). It was described based on a single male and has not known of its labrum, mandible and maxillule. However, the maxilla is, as illustrated in the original description, not a form of the Clausiidae but a form of the Lichomolgoidea; its basis (distal segment) is curved, attenuated and claw-like distally. Moreover, the basis carries a relatively large medial seta (seta I), as in some copepods in the Lichomolgoidea. Within the Lichomolgoidea, it seems to belong to the Sabelliphilidae or the Polyankyliidae considering the antenna has a strong claw on the second endopodal segment and multiple claws on the terminal endopodal segment. Legs 1-4 of Stockia lack an inner coxal seta and its legs 3 and 4 lack an endopod. The latter features are considered to be of the Polyankyliidae and the genus Stockia would better to be placed in the Polyankyliidae .

With the transfer of the three genera, Terebelliphilus , Octophiophora and Stockia , into the Polyankyliidae , this family now contains five genera which may be distinguished using the key below. Known hosts of these copepods are serpulid polychaetes ( Serpulidae ) for Octophiophora and terebellid polychaetes ( Terebellidae ) for Polyankylis ovilaxa n. sp. and Sewelloya plana n. gen. n. sp. Although P. orientalis and P. australis are not known of their hosts, these two species are presumed to be dislodged from polychaetes. Stockia was likely dislodged from a polychaete associated with scleractinian coral.

A key to genera of the Polyankyliidae

(based on females)

1. Legs 1-3 with 2-segmented exopod · · · · · · · · · · · · · · · Stockia

– Legs 1-3 with 3-segmented exopod · · · · · · · · · · · · · · · · · · · · · · · · · 2

2. Body vermiform; antennule 5-segmented; endopod of legs 1-3 rudimentary · · · · · · · · · · · · · · · · · · · · · · · · · Octophiophora

– Body not modified; antennule 6-segmented; endopod of legs 1-3 well-developed and 2-segmented · · · · · · · · · · · 3

3. Leg 4 with 3-segmented exopod; legs 1-3 without inner coxal seta; fourth pedigerous somite narrow, without epimera · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Terebelliphilus

– Leg 4 with 1- or 2-segmented exopod; legs 1-3 with inner coxal seta; fourth pedigerous somite with epimera · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 4

4. Terminal segment of female maxilliped terminated in long spiniform claw or spine; leg 5 with free exopod bearing 2 elements · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Polyankylis

– Terminal segment of female maxilliped simple and tapering, with 2 small setae; leg 5 represented by 3 setae · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Sewelloya n. gen.