Metapontius Hansen, 1923

Johnsson, Rodrigo & Neves, Elizabeth G., 2005, A revision of Metapontius (Siphonostomatoida: Artotrogidae) with the description of a new species associated with an octocoral from Eniwetok Atoll, Marshall Islands (USA), Zootaxa 1035, pp. 51-59 : 53

Metapontius Hansen, 1923

Cephalothorax of the female greatly expanded; in the male, considerably narrower. Pedigerous somite 4 with sternite short and not produced backwards. Urosome 5­segmented with caudal rami rather large. Antennule, 8­ to 14­segmented in female and 17­segmented in male. Antenna, endopod segments II and III fused, exopod 1­segmented. Mandibular palp absent. Maxillule with inner lobe slightly longer than outer lobe, each one bearing 2 distal setae. P4, exopod 3­segmented, endopod 2­segmented. P5 consisting of short, smooth seta near insertion of small, free segment, armed with two distal smooth setae.

Remarks

The original description provided by Hansen (1923) listed two character­states, which can now be attributed to the species itself and not the genus: 1) the 14­segmented antennule on the female and 2) the prosome with posterolateral corners nearly rectangular and not produced.

Several studies have indicated that the number of antennule segments varies within the genera of the Artotrogidae ( Kim 1998, 1996; Johnsson et al. 2002; Johnsson & Rocha 2002) and thus the number of antennule segments is no longer used as a generic character.

The original diagnosis of the genus Metapontius states “prosome with the postero­lateral corners nearly rectangular and not produced”. This character­state is now considered a specific variation as it is only found on pedigerous somite 4 of the new species. Consequently, the genus diagnosis is emended to restrict the condition to this particular body somite.