Asteroidea, de Blainville, 1830

Pourvali, Naser, Aliabadi, Mohammad-Ali Salari, Salamat, Negin, Hesni, Majid Askari, Ranjbar, Mohammad Sharif, Carter, Hugh & Price, Andrew. R. G., 2025, Systematics, distribution and ecology of sea stars (Echinodermata: Asteroidea) from Iranian waters of the Persian Gulf and a revised identification key, Zootaxa 5647 (3), pp. 201-234 : 204-205

Key to the Asteroidea of the Persian Gulf

1 Lack of terminal disc in tube feet; body flattened along actinal/abactinal axis; abactinal plates paxilliform............... 2

- Tube feet cylindrical with terminal disc; body not conspicuously flattened along actinal/abactial axis.................. 11

2 Body edge defined by inferomarginal playes only; superomarginal plates indistinguishable ( Luidiidae )................. 3

- Edge of body defined by both conspicuous supero-marginal and inferomarginal plates ( Astropectinidae )............... 6

3 Colour with a bold ‘checkerboard’ pattern on the upper side (retained after preservation); seven to nine arms; abactinal paxillae lack enlarged central spines............................................ Luidia maculata Müller & Troschel, 1842

- No distinctive checkerboard colour pattern, although dark radial stripes may be present; five or six arms; some, or many of the abactinal paxillae with large, sharp, conspicuous spines....................................................... 4

4 Long slender pedicellariae on the outer part of some adambulacral plates......................................... 5

- No pedicellariae on adambulacral plates............................................. Luidia prionota Fisher, 1913

5 Furrow and subambulacral spines arranged in 1 or 2 zigzag transverse rows, abactinal surface uniformally coloured................................................................................... Luidia hardwicki ( Gray, 1840)

- Furrow and subambulacral spines in single transverse row, abactinal surface with long dark stripe along mid-radial line............................................................................ Luidia quinaria von Martens, 1865

6 Supero-marginal plates with a well-developed spine rising close to the abactinal or upper edge of the plate.............. 7

- Supero-marginal plates with spine absent or present, if present then all but the most basal arising from the middle or outer part of the plate, not the upper edge.......................................................................... 8

7 Supero-marginal spines present on all plates, no spines missing towards the proximal end....................................................................................... Astropecten polyacanthus phragmorus Fisher, 1913

- Several supero-marginal plates at proximal end missing spines and/or reduced in size............................................................................... Astropecten polyacanthus polyacanthus Müller & Troschel, 1842

8 Supero-marginal plates lacking spines, although spines present on infero-marginals; two broad, spatulate spines on the middle part of each adambulacral plate........................................... Astropecten monacanthus Sladen, 1883

- Supero-marginal plates each with a spine on the outer part of the plate; adambulacral plates lacking broad, spatulate spines.. ................................................................................................... 9

9 Paxillae with numerous central granules (up to c. 35 in larger specimens); mid-radial arm paxillae often also with multiple central granules............................................................ Astropecten pugnax Koehler, 1910

- Paxillae rarely with more than a dozen granules; midradial arm paxillae reduced to only a single central granule......... 10

10 R not exceeding 45 mm; supero-marginal plates fairly small, surface covered with small spinelets; large prominent madreporite............................................................. Astropecten indicus Döderlein, 1888

- R regularly exceeding 50 mm; supero-marginal plates broad, and their surface covered with large, polygonal, flattened granules; madreporite small, inconspicuous.................................. Astropecten hemprichi Müller & Troschel, 1842

11 Marginal plates large, forming a conspicuous side-wall to the body; abactinal surface usually flat, rarely convex; no papulae on the lower side ( Goniasteridae ) ......................................................................... 12

- Marginal plates not conspicuous when viewed from above, very thin where these define the body edge; abactinal surface usually strongly convex; papulae usually present on lower side................................................ 14

12 Large, conspicuous bivalved pedicellaria, valves usually 5–6 times as wide as thick, covering half the diameter of the underlying plate; adambulacral plates baring three series of spines; five primary radials also with consipicuous enlarged, pointed tubercles.............................................................. Anthenea rudis Koehler, 1910

- No conspicuous large bivalved pedicellariae present, only minute and and hard to distinguish from granules where present; at most a single adambulacral spine; primary radials lacking conspicuous tubercles.................................. 13

13 Arms slender and acute at tips; supero-marginals narrow, not more than a fifth of r interradially; not more than one infero-marginal spine, sometimes none; adambulacral spine absent............................ Stellaster children Gray, 1840

- Arms blunt at the tip and usually broad throughout their length; superomarginals broad, ½ – ⅓ of r interradially; adambulacral spine prominent....................................................... Goniodiscaster insignis ( Koehler, 1910)

14 More than 10 arms baring large, conical, isolated spines up to 30mm in length spread across the abactinal surface................................................................................ Acanthaster planci ( Linnaeus, 1758)

- Arms typically 5–6, lacking prominent spines.............................................................. 15

15 Arms short and blunt; a supradorsal membrane present supported by the tips of the abactinal spines support a supradorsal membrane which forms a cavity with the abactinal surface to form a cavity within..................................................................................................... Euretaster cribrosus (von Martens, 1867)

- Arms long and cylindrical or short and rounded; supradorsal membrane always absent............................. 16

16 Arms cylindrical in cross-section ( Ophidiasteridae ) ........................................................ 17

- Arms not cylindrical in cross section, varying from flattened to triangular........................................ 20

17 Abactinal plates in more or less regular longitudinal series for the whole length of the arm although margins often obscured by thick smooth skin, armament of any kind absent from all but adambulacral plates, which bear narrow furrow spines..................................................................................... Leiaster leachi ( Gray, 1840)

- Abactinal plates irregularly arranged, plates rounded and completely covered in granules with margins not usually obscured by skin,, adambulacral plates with granule shaped furrow spines................................................. 18

18 Subambulacral spines in two series, arranged obliquely to give a ‘herring bone’ pattern to the underside of each arm; no granules between the furrow spines within the furrow................................. Linckia guildingi Gray, 1840

- Subambulacral spines very low, surrounded by granulation, usually only a single series presented but if two series, all the spines isolated from each other, furrow spines surrounded with granulation............................................ 19

19 Arms normally five in number with a single madreporite; arms fairly stout and blunt at the tip; color in life blue or bluishgreen................................................................... Linckia laevigata ( Linnaeus, 1758)

- Arms irregular in length, normally two madreporites; arms slender and attenuate at the tip; color in life variegated, reddish, brownish, purplish or khaki-colored with yellowish, sometimes more or less uniform.... Linckia multifora ( Lamarck, 1816)

20 Interradial areas extensive; arms tapering, stellate or short (sometimes to the extent that they are almost undifferentiated from the disc); abactinal surface reticular with secondary plates linking larger primary plates and leaving conspicuous porous areas in between ( Oreasteridae ) ............................................................................. 21

- Interradial areas extensive or reduced, arms only short and body stellate when R <30 mm; abactinal skeleton either consisting of closely imbricated plates with small interstitial pores ( Asterinidae ) or body covered in thick skin with a series or spines along the carinal and superomarginal plate rows so that arms appear acutly triangular in cross-section ( Asteropseidae ) ... 22

21 Body pentagonal when young, becoming almost spherical in larger specimens; marginal plates concealed within thickened skin............................................................... Culcita coriacea, Müller & Troschel, 1842

- Arms well developed, not reduced and body never spherical in appearance; distal marginal plates covered with distinct, even sized and usually projecting granules................................... Pentaceraster mammillatus ( Audouin, 1826)

22 Body covered by smooth thick skin which obscures underlying abactinal plates; edge of the body defined by superomarginals which bear prominent conical spines........................................ Asteropsis carinifera ( Lamarck, 1816)

- Abactinal plates quadrangular or cresent shaped, not obscured by skin; edge of the body defined by inferomarginals which are armed only with clusters of spinelets or granules........................................................... 23

23 Usually more than 5, sometimes up to 9 arms of unequal size, often asymmetrically arrayed; multiple inconspicuous madreporites.............................................................. Aquilonastra burtoni ( Gray, 1840)

- Typically 5 arms, sometimes 4 or 6, equal or subequal; form usually symmetrical; single conspicuous madreporite, very rarely two or more......................................................................................... 24

24 Pedicellariae absent............................................. Aquilonastra samyni O’Loughlin & Rowe, 2006

- Pedicellaria present................................................................................... 25

25 Abactinal spinelets thick, up to 12 on each proximal carinal plate................ Aquilonastra iranica ( Mortensen, 1940)

- More than 15 thin, small spinelets per proximal carinal plate, typically more than 24............................... 26

26 Fewer than 25 spinelets per proximal carinal plate, superomarginals with 10 spinelets (R = 19mm).................................................................................. Aquilonastra watersi, O’Loughlin & Rowe, 2006

- Up to 38 spinelets per proximal carinal plate, inferomarginals with 21 spinelets per plate (R = 22mm)...... Aquilonastra sp.