Paraferdina plakos, Mah, Christopher L., 2017

Mah, Christopher L., 2017, Overview of the Ferdina - like Goniasteridae (Echinodermata: Asteroidea) including a new subfamily, three new genera and fourteen new species, Zootaxa 4271 (1), pp. 1-72 : 63-65

Paraferdina plakos n. sp.

Figure 22 A–F

Koehler 1910: 143,147, pl. 16, figs. 4, 5 (as Ferdina offreti in part) Marsh and Price 1991: 69 (as P. sohariae )

Etymology. The species epithet is derived from the Greek plakos for “plate” (noun held in apposition).

Diagnosis. This species has much larger and wider superomarginal plates which encroach onto the abactinal surface forming a very wide marginal edge (65–80% of the disk radius) to this species. Abactinal, marginal and actinal surfaces are all covered by continuous granular tegument with no bare region. Glassy embossed nodules are absent.

Taxonomic notes. Examination of the paratype of Paraferdina sohariae figured by Marsh and Price (1991: Fig. 4 ) in contrast shows much less prominent superomarginals with smaller but more convex abactinal plates and with a more angular contact with the abactinal surface. Superomarginals in Paraferdina plakos n.sp. compose approximately 65–80% of the abactinal surface across the arm base, whereas superomarginals in P. sohariae comprise only approximately 25–30% of the distance across the arm base. Although arm shape varies between the two figured individuals, plate patterns are consistent and when further images of this species was surveyed (see below) it was clear that arm shape was variable across different individuals. Specimens examined were slightly larger (R= 3.7–4.1 cm) than those identified by Price and Marsh (1991) as P. sohariae (R= 3.3–4.3 cm) which argues against morphological differences as size-based.

As indicated below, this species is frequently misidentified as Fromia monilis , most likely due to its nearly similar color pattern (red and white). However, Paraferdina differs in that the granular tegument completely covers the adambulacral plate surface and the marginal plates along the arms covers a significant part of the arm surface.

Conservation note. In the course of study of this species, images from approximately twelve aquarium and pet shops were consulted on social media (Facebook, etc.) and the internet with a several images (n>20 files) displaying over 30 individuals identified as being for sale, but almost always misidentified as either Fromia or Fromia monilis , and was labelled: “pebbled star”, “red marble”, “marbled Fromia ”, “Indian sea star”, “tile starfish” among others. Three sets of images were identified as having been collected from Sri Lanka whereas most of the others were without collection data. This indicates that this species, has either directly or indirectly become a target for the aquarium fishery. Because very little about the biology of this species is known, this species’ sustainability and potential ecological importance are important future research and conservation considerations.

Occurrence. Racha Yai Island, Andaman Sea, Thailand, Madagascar 30– 54 m . Note also that some of the commercial images depicting this species indicated collection from Sri Lanka but this could not be verified.

Description. Body stellate (R:r=3.15–3.36), arms triangular ( Fig. 22 A) to more blunt-tipped and finger-like in shape ( Fig. 22 D). Body stout. Granulated tissue layer covers body surface.

Abactinal surface composed of large, round to polygonal plates abutted against one another with smaller (<15% of diameter) plates present between them ( Figs 22 A–E). Largest plates are present along arms, smallest most numerous plates present on disk and proximally on arm. Larger plates variable, but when present are weakly convex, circular to polygonal on disk. Arms dominated by large polygonal plates with few to no observed smaller plates ( Figs. 22 A, B, D, E). Abactinal plates highly variable with different arms on the holotype not showing identical plate shapes, sizes or patterns. These larger plates forming large, wide to equal sized, round to polygon shields along the radius of each arm ( Figs 22 B, E), with many in direct contact with superomarginal plates where they encroach onto the abactinal surface. The holotype ( Sri Lanka) shows smaller plates on the abactinal surface whereas the paratype ( Madagascar) ( Fig. 22 A) displays fewer arm plates and has a darker more granular tegument. Surface completely covered by fine, continuous cover of granules. Papulae, three to 20, forming variably sized patches between larger plates, conspicuously extending through the granular tegument. Granules and papulae extend along arm surface to arm tip along narrow strip between superomarginals to arm tip. Madreporite triangular in shape, abutted by approximately three abactinal plates. Pedicellariae not observed. Anus with five spatulate, blunt spines. Papular regions between large to mid-sized shield-like plates dark in color. Granules obscure boundaries between plates.

Marginal plates, 18–24 per interradius, each plate broad and very wide, shield-shaped with all surfaces covered by a continuous layer of granules obscuring boundaries between plates ( Figs. 22 A, B, D, E). Abactinal and marginal plate series are swollen and sit above the body surface. Superomarginals and inferomarginals slightly offset from one another. Superomarginal plates form prominent wide border around edge and encroaching onto abactinal surface. Distalmost two to four superomarginal plates abutting along midline with zig-zag shaped contact along midline. Most are in homogeneous, serial order but a smaller number of plates in irregular series on one arm was observed, as well as some irregular plates on arm tips. Papulae, which were present abactinally are absent on marginal surface. As with the abactinal surface, regions between marginals are darker in color. No pedicellariae observed. Terminal plate triangular, arm upturned.

Actinal surface composed of approximately two and a half series of actinal intermediate plates ( Figs. 22 C, F). Individual plates, weakly convex, quadrate to polygonal in shape. Actinal plates extend along ~90% of arm length pinching out about two to three plates prior to terminus. Adambulacrals quadrate in shape, covered by granules that are slightly larger than those which cover remainder of actinal surface. Actinal granules differ from abactinal and marginal surface in that color is consistently light across the surface but boundaries between plates are obscured by granules. No pedicellariae observed. Furrow spines, short and blunt, one or two per adambulacral. Below furrow spine tip, surface covered by granules. One large, blunt spine directed into mouth per plate. Furrow spines on oral margin slightly thicker than those more distally along arm. Granules on oral surface adjacent to oral plates slightly more coarse than those on actinal surface.

Numerous images of this species from crowd-sourced image banks and online aquarium shops show living colors for this species as white, yellow to red plates with striking darker red, orange to bright yellow coloring the interstitial granular regions between them. Some show dark red/orange disk granulation with white abactinal and marginal plates and yellow to orange arm tips. Papulae are represented by dark spots are present among the darker interstitial granular regions.

Material examined. Holotype: MNHN-IE-2013-6604; Racha Yai Island , Thailand, 30 m; Coll. S. Patamokaithin; 1 dry spec. R=4.1, r=1.3 . Paratype: MNHN-IE-2007-1099; Madagascar, 14°31.9’S, 47° 26.54’E, 54 m; Coll. Bouchet & Kantor, 14 July 2009, St. CP 3288 N/ O Miriky; 1 wet spec. R=3.7, r= 1.1.

Figures

FIGURE 4. Ferdina flavescens. MNHN-IE- 2013 - 6603. Scale Bar = 2.0 mm. A. Abactinal surface. C. Oral surface. E. Close up actinal surface, furrow spines and other adambulacral features. F. sadhensis. Paratype USNM E 41400. Scale Bar = 3.0 mm. B. Abactinal surface. D. Oral surface. F. O ral surface detail.

FIGURE 22. Paraferdina plakos n. sp. A – C: Paratype, MNHN-IE- 2007 - 1099. Scale Bar = 1.8 mm. A. Abactinal surface. B. Abactinal and superomarginal detail. C. Actinal surface. D – F: Holotype MNHN-IE- 2013 - 6604, Scale Bar = 6.0 mm. D. Abactinal surface. E. Superomarginal and abactinal detail. F. Actinal surface.