Psychropotes verrucicaudatus Xiao, Gong, Kou & Li, 2019

Yu, Chuan, Zhang, Dongsheng, Zhang, Ruiyan & Wang, Chunsheng, 2022, New psychropotid species (Echinodermata, Holothuroidea, Elasipodida) of the Western Pacific with phylogenetic analyses, ZooKeys 1088, pp. 99-114 : 99

Psychropotes verrucicaudatus Xiao, Gong, Kou & Li, 2019

Figs 5 , 6 , 7

Psychropotes verrucicaudatus Xiao, Gong, Kou & Li, 2019: 421-430.

Material examined.

Catalog number: RSIO6018004, adult specimen, collection number: DY60-JL180-B04, 13.569°N, 134.352°E, 25 January 2021, 2469 m; Catalog number: RSIO6017005, adult specimen, collection number: DY60-JL170-B05, 12.079°N, 134.860°E, 8 January 2021, 2361 m.

Description.

RSIO6018004. Specimen resembles a barbell after collection, approximately 20 cm in length before preservation 10% seawater formalin (Fig. 5C, D ). Before preservation, height of appendage was approximately 50 mm, and width at base approximately 30 mm (Fig. 5C, D ). Dorsal skin transparent with brownish red color on seabed and dark brown on deck. Warts covering dorsal skin and appendage; giant ossicles in warts visible (Fig. 5E, F ). Approximately 30 pairs of degenerated tube feet arranged in two rows along middle of ventrum. Sixteen tentacles forming a circle. Brim broad and covered with warts on dorsum.

A giant cross with four arms visible in each wart. Arms 800-1000 μm in length, and maximum width between large arms approximately 500 μm. Arm flexion approximately 250 / 400 μm (Fig. 6A-D ). Height of central rudimentary apophyses approximately 200-300 μm. Ventral ossicles divided into two types: primary cross with spiny arms (Fig. 8A, C ) and cross with three arms (Fig. 7B ), length of arm approximately 200 μm. Primary crosses with spinous arms in dorsum (Fig. 7D-F ) and brim (Fig. 7H-J ); arms up to 200 μm in length. Dorsal ossicles with spinous rod, 170 μm in length (Fig. 7G ), and large primary crosses with spiny arms in brim (Fig. 7K ). Tentacles with rods with irregular shape (Fig. 7L-R ). Large rod with two apophyses at the end, approximately 900-1000 μm in length (Fig. 7L-M ); small rod with apophyses in middle area was approximately 200 μm in length (Fig. 7N ). Other rods with spiny arms, 500-800 μm in length (Fig. 7O-R ).

RSIO6017005. Specimen approximately 18 cm in length, height of appendage approximately 40 mm, and width at base approximately 20 mm. Mouth and anus ventral. Skin transparent, light brown color. Dorsal skin and appendage covered with warts; warts also present in dorsum of brim. Giant ossicles visible in warts. Tentacles damaged, more than 12. Ossicles as in RSIO6018004.

Type locality.

Jiaolong Seamount, South China Sea, Western Pacific Ocean, sandy bottom, depth 3615 m.

Type species.

Psychropotes longicauda Théel, 1882.

Distribution.

Known from Jiaolong Seamount of South China Sea and Kyushu-Palau Ridge.

Intraspecific variation.

The specimens were clearly a new record for the South China Sea, as the species was previously known only from the Jiaolong seamount. The present specimens differed from those of Xiao et al. (2019) in external morphology and the ossicles. Due to the bad preservation, Xiao et al. (2019) could not observe the ossicle assemblage of the warts, which was possible in the specimens here under study.

The intraspecific differences can be listed as follows: (1) In the present specimens, the skin was transparent and the color was darker than that of the type specimen; (2) The width of the appendage at the base was also larger than that of the type specimen; (3) The length of the primary crossing arms distributed in the dorsum, ventrum, and brim was longer than that of the type specimen. Furthermore, the spinous rod of the dorsal ossicles was not present in the type specimen, and the ventral body wall of the specimens did not possess the tripartite ossicles of the type specimens; and (4) Most of the ossicles of the tentacles in our specimens were the same as those of type specimen, but longer.

Figures

Figure 5. A, B Psychropotes verrucicaudatus Xiao, Gong, Kou & Li, 2019 (RSIO 6018004) in situ C, D specimen (RSIO 6018004) before preservation E, F red arrows point to the giant ossicles, specimen (RSIO 6018004) after preservation in 10 % seawater formalin. Scale bars: 5 cm (A-E); 1 cm (F).

Figure 6. Psychropotes verrucicaudatus A-D giant ossicles from the dorsal warts.

Figure 7. Psychropotes verrucicaudatus ossicle from A-C ventral body wall D-G dorsal body wall H-K brim L-R tentacle.

Figure 8. Bayesian inference (BI) and maximum likelihood (ML) trees based on the concatenated sequences. The Bayesian posterior probabilities (BI) and Maximum likelihood bootstrap (BS) values are shown as BI / ML at each node. Scale bar indicates the evolutionary branch length.