Henricia margarethae, Kobayashi & Kohtsuka & Fujita, 2021

Kobayashi, Itaru, Kohtsuka, Hisanori & Fujita, Toshihiko, 2021, Two new deep-sea species of the genus Henricia (Asteroidea: Spinulosida Echinasteridae) from Japanese waters, Zootaxa 4903 (1), pp. 89-104 : 91-93

Henricia margarethae n. sp.

Figs. 2A , 3 A–I, 5A, B

[New Japanese name: Shirayuki-hime-hitode]

Type Material: Holotype. NSMT E-13349, Sagami Bay , off Johgashima Island, Kanagawa, Japan (35°6.1617’N, 139°34.286’E), 267–280 m depths, collected by the R / V Rinkai -Maru, 10 January 2012, fixed in 99.5% ethanol and dried later; R 87 mm, r 13 mm . Paratype. NSMT E-7186, off Hamakanaya , Chiba, Japan, 200–400 m depths, collected by the fishing boat Chogoro-Maru, 15 April 2004, fixed in ethanol of an unknown concentration ; R 86 mm, r 14 mm.

Type Locality: Sagami Bay , 267–280 m.

Diagnosis. Abactinal skeleton is an irregular, open meshwork. Papular areas are larger than abactinal plates, containing 1 to 9 papulae. Abactinal spines clavate, bluntly pointed, serrated distally, and arranged in two or more series. Intermarginal series extends to 1/3 to 1/2 of R. Pseudopaxilla widely separated from each other. Superomarginal, inferomarginal, ventrolateral, and adambulacral plate is each with 5 to 20 spines. Ventrolateral series are multiple. The ventrolateral series next to the innermost series is the longest. Subambulacral spines arranged in two or more rows. Furrow spines 2 on most adambulacral plates in a vertical row.

Description of Holotype. Arms five, sub-cylindrical in shape, slender, gradually tapering to arm tip. R/r ratio is 6.7. Each abactinal interradial area has a linear fold between two arms ( Figs. 2A , 3A ). The abactinal skeleton is an irregular open meshwork, which is constituted by a lot of oval to rod-shaped or quadrilobate abactinal plates. Abactinal plates are partially imbricated each other. Each abactinal papular area is larger than the surrounding plates, containing 1 to 9 (mainly 3 to 5) papulae, and 1 to 3 secondary abactinal plates ( Figs. 3B, C ). Each abactinal plate bears 1 to 12 abactinal spines which tend to be arranged in irregular two or sometimes more than two linear or curved rows ( Fig. 3D ). Abactinal spines are grouped together by an integument to form pseudopaxillae which are not arranged in regular series ( Figs. 3A, B ). Pseudopaxillae are widely separated from each other by relatively sunken papular areas ( Figs. 3B, D ). A madreporite is located at the margin of the disc with numerous spines on its surface.

Abactinal spines are stout and bluntly pointed and 0.28 to 0.44 mm in length. Proximal half of the spines is uniformly smooth, but distal half of the spines is serrated by numerous thorns. The width of the spines is thicker in the distal half to two-thirds than at the base, providing club-shaped appearance ( Fig. 5A ).

Supero- and inferomarginal plates are quadrilobate and are arranged in two regular longitudinal series ( Figs. 3E, F ). Each superomarginal plate bears 6 to 15 spines, and each inferomarginal plate bears 6 to 18 spines ( Fig. 3G ). The supero- and inferomarginal spines are irregularly arranged in transverse two or three rows (rarely more than three) on each plate ( Fig. 3G ). These series of marginal plates are separated each other from proximal-most to at least proximal one-third the length of the arm. Superomarginal series gradually come closer to inferomarginal series as it approaches to the distal direction ( Figs. 3E, F ). A meeting point of supero- and inferomarginal series is located between proximal one-third to half the length of the arm. Beyond the meeting point, supero- and inferomarginal series adjoin completely to the terminal plate. An interspace between the supero- and inferomarginal series is filled with many quadrilobate or rod-shaped intermarginal plates ( Figs. 3E, F ). Intermarginal plates are arranged in three longitudinal series, but these series tend to be irregular at the arm base. The intermarginal series next to the superomarginal series is the longest ( Fig. 3E ), which extends proximal one-third to half the length of the arms. The other two intermarginal series are confined within proximal one-third the length of the arms. Most superomarginal plates in contact with intermarginal plates. There are no small rod-shaped intermarginal plates connecting two other intermarginal plates longitudinally ( Figs. 3E, F ). One to three irregular series of papulae are present between the superomarginal and inferomarginal series.

Ventrolateral plates are quadrilobate, rod-shaped and are arranged in three longitudinal series ( Fig. 3E, F ). The first series extends one-third to half the length of the arms. The second series is the longest and exceeds two-thirds the length of the arms. The third series never reach to one-third the length of the arms. Each ventrolateral plate bares 5 to 14 spines on their central tubercle in two or more irregular rows ( Figs. 3 E–H). Two to three series of papulae are present between the inferomarginal and adambulacral series.

Most adambulacral plates with 2 (rarely 1) furrow spines deep in the furrow in a vertical row ( Fig. 3I ) and 7 to 15 subambulacral spines in two or more irregular transverse rows ( Fig. 3H ).

The color in life is uniform white ( Fig. 2A ).

Variations in Paratype. Each superomarginal plate bears 5 to 17 spines, and each inferomarginal plate bears 11 to 20 spines.

Ventrolateral plates are arranged in four longitudinal series. Except for the second series, all ventrolateral series never exceed proximal one-third the length of the arm. Amongst them, the fourth ventrolateral series is the shortest, and the first series are shorter than third series. The ventrolateral plates bear 6 to 15 spines.

Adambulacral plates have 6 to 15 subambulacral spines in two or more irregular transverse rows.

Distribution. Sagami Bay and Uraga Channel, around the Miura peninsula, central Japan. Bathymetric range is 200– 400 m.

Etymology. The specific name is dedicated to Margaretha Von Waldeck who was the model for the princess in Grimm’s Snow White ( Sander, 1994) who was described as having pale, white skin. This species also shows white color in life. The Japanese name “shiaryuki-hime” means Snow White, and “hime-hitode” is commonly used for the species name of the genus in Japan.

Figures

FIGURE 2. A. Henricia margarethae n. sp. Holotype NSMT E-13349. Living specimen. B. Henricia fragilis n. sp. Holotype, NSMT E-13165. In situ image by ROV Hyper-Dolphin at 1806 m in depth off Hahajima Island. The specimen is associated with an unidentified glass sponge.

FIGURE 3. A–I. Henricia margarethae n. sp. Holotype, NSMT E-13349. J. Henricia arcystata Fisher, 1917. Holotype, USNM 37007. A. whole body, abactinal and actinal views. B. part of abactinal surface, near the base of arm. C. denuded abactinal surface at proximal-most portion of arm, showing secondary abactinal plates (arrow heads). D. abactinal pseudopaxillae from proximal-most portion of arm. E. part of denuded ventrolateral surface, near the base of arm. F. part of denuded ventrolateral surface at one-third to half the length of arm. G. part of lateral surface at one-third to half the length of arm. H. part of actinal surface, one-third to half the length of arm. I. furrow spines, the Arabic numerals 9 to 12 indicate furrow spines which stand on 9th to 12th adambulacral plates, respectively. J. part of lateral surface, one-third to half the length of arm. Abbreviations: (S) superomarginal series, (I) inferomarginal series, (V1) first ventrolateral series, (V2) second ventrolateral series, (V3) third ventrolateral series, (A) adambulacral series. Scale bars indicate 10 mm for A, 1 mm for B–J. Proximal is left in B–J.

FIGURE 5. SEM images of lateral and top view of abactinal spines from basal arm. A. Henricia margarethae n. sp. Holotype, NSMT E-13349. B. H. margarethae n. sp. Paratype, NSMT E-7186. C. Henricia fragilis n. sp. Holotype, NSMT E-13165. Scale bar indicates 0.1 mm.