Itostenhelia polyhymnia sp. nov. L-form

(Fig. 42)

Locality. South Korea, South Sea, Gwangyang Bay, sampling station 10, muddy sediments, 34.920944°N 127.785528°E (Fig. 1) .

Specimens examined. One female dissected on one slide (collection number NIBRIV0000232698), two females destroyed for DNA sequence (one amplification successful, Code 0271), 30 July 2012, leg. K. Kim.

Remarks. Only three females of this large morphotype were collected, two of which were destroyed for DNA analysis. All were significantly longer and larger than the typical Itostenhelia polyhymnia, and the one examined morphologically measured 511 µm. Other differences include somewhat longer caudal rami (arrowed in Fig. 42A), proportionately larger genital double-somite (arrowed in Fig. 42A), and two sensilla on cephalothorax and one on first urosomite missing (all arrowed in Fig. 42A). However, all other morphological details are the same, including the labrum (Fig. 42C) and fifth leg (Fig. 42D), and the COI sequence is indistinguishable too (although it is very short). Thus we have to conclude that this is either dimorphism or a chance mutation. The latter hypothesis seems more likely, as the L-form is very rare compared to the typical form, and all three specimens collected were found in one sample, so there is a chance that they are kin. We have no doubt that these two forms are conspecific, but they are listed separately to better alert readers about their existence.