Porirualia pyriformis (Song, Kim & Chang, 2003) comb. nov.

Parastenhelia pyriformis Chang, Kim & Chang, 2003

Original description. Song et al. (2003): 221–227; Figs 1–4; Table 1.

Type locality. South Korea, Jeju Island, Sehwa Beach (33°28’07” N, 126°54’43” E); shallow sublittoral zone .

Differential diagnosis. This coincides with Song et al. ’s (2003) description of Parastenhelia pyriformis .

Notes. Song et al. (2003) added a second record from Seungbong Island in the Yellow Sea where it was found to be associated with macroalgae ( Zostera japonica) on sandy bottoms (see also Song et al. 2012).

The two species can be distinguished, in both sexes, by (a) rostrum size (reaching to distal margin of segment 5 of the antennule in Po. megarostrum vs halfway segment 4 in Po. pyriformis), (b) antennary morphology (allobasis partially divided by surface suture and exp-2 with four setae/spines vs allobasis without trace of original segmentation and exp-2 with five elements, i.e. with additional apical seta), (c) armature of mandibular basis (with one spine and three setae vs one spine and two setae), (d) length:width ratio of P1 enp-2 (2.2 vs 1.3), and (e) armature of P3–P4 exp-3 (distal inner seta present and short vs absent). In addition, females can be differentiated by the proportional segment lengths in the antennule (segment 1 longest in Po. megarostrum vs segment 2 longest and entire appendage more slender in Po. pyriformis) and P5 morphology (L:maximum W ratio 2.2 and distal outer seta longest in Po. megarostrum vs 3.25 and inner distal seta longest in Po. pyriformis). Males differ in the segmentation of P2–P3 endopods (3-segmented vs 2-segmented) and the number of elements on the P5 exopod (six vs five).