Pycnogonum spatium Takahashi et al. 2007

Lee, Damin & Kim, Won, 2020, New species of Pycnogonum (Pycnogonida: Pycnogonidae) from Green Island Taiwan, with an additional note on the holotype of P. spatium, Zootaxa 4750 (1), pp. 122-130 : 128-129

Pycnogonum spatium Takahashi et al. 2007

Figures 3 C–D, 5A–F

Pycnogonum spatium Takahashi et al., 2007: 73–75 , fig. 5

Material examined. Holotype, ICHUM3172 , Southeast of Amami Island , Kagoshima, Japan, 28°09.20’N, 129°31.50’E, 332–334 m, beam trawl, Y. Takahashi, 25 May 2004.

Remarks. Although Takahashi et al. (2007) described P. spatium as having granular integument, the body integument being pitted ( Fig. 3C ), and only the dorsal surface of legs being granulated and pitted ( Fig. 3D ). The proboscis length was recorded as 0.47 mm, while it is actually 0.89 mm ( Fig. 5B ). Takahashi et al. (2007) determined the P. spatium holotype to be a female based on gonopores being on the dorsal surface of coxa 2 of all legs ( Fig. 5F ), however the present observation reveals that there is a gonopore on the ventrodistal surface of coxa 2 on each fourth leg ( Fig. 5E ), which shows the trait of a male. In this case, we can suggest two possibilities, the first being that the specimen is a hermaphrodite and secondly the female gonopores were misdiagnosed and represent coxal pelliculae (vide Staples, 2007), in which case the specimen is a male belonging to the subgenus Nulloviger . To solve this problem, we need additional collection of specimens and research to distinguish the coxal pellicula from the gonopore.

Figures

FIGURE 3. Integument. Pycnogonum (Nulloviger) granulatum sp. nov.; A–B. A, granulated integument of abdomen, dorsal view; B, granulated integument of femur, distal surface. P. spatium; C–D. C, pitted integument of abdomen, dorsal view; D, granulated and fitted integument of femur, distal surface. All images are observed under the light microscope (Olympus BX51, Japan). Scale bars: 0.1 mm (A, C).

FIGURE 5. Pycnogonum spatium, holotype.A, trunk, dorsal view; B, trunk, lateral view; C, trunk, anterodorsal view; D, third leg, long spine on femur broken; E, fourth leg, arrow indicating gonopore; F, second leg, arrow indicating coxal pellicula. Scale bars: 1 mm (A–B); 0.5 mm (C–D); 0.1 mm (E–F).