Rhopalophthalmus

Hanamura, Yukio, Murano, Masaaki & Man, Alias, 2011, Review of eastern Asian species of the mysid genus Rhopalophthalmus Illig, 1906 (Crustacea, Mysida) with descriptions of three new species, Zootaxa 2788, pp. 1-37 : 35-36

Key to species of Rhopalophthalmus

1 Eyes elongated, longer than antennular peduncle.............................................. R. flagellipes Illig

- Eyes moderate in length, falling far short of anterior end of antennular peduncle.................................... 2

2 Carapace without anterior dorsal nodule or discernible only as feeble swelling, if present............................ 3

- Carapace with distinct anterior dorsal nodule................................................................ 8

3 Ten or more spines of antennal sympod arranged in true conical form........................... R. dakini O. Tattersall

- Fewer than 10 spines of antennal sympod not arranged in conical form but composed of 1–3 prominent mesial spines flanked usually by a few to several much smaller additional spines, showing notable difference in height between them........... 4

4 Antennal sympod possessing 3 prominent spines; antennal scale more than 7 times length of its width................................................................................................... R. chilkensis O. Tattersall

- Antennal sympod possessing 1 or 2 prominent spines; antennal scale utmost 7 or lesser than 7 times length of its width.... 5

5 Telson without discernible waist near base................................................................. 6

- Telson with discernible waist near base.................................................................... 7

6 Antennal sympod bearing 1 prominent mesial spine and 1 small additional spine; carpo-propodus of seventh thoracic endopod composed of 4 sub-segments.......................................................... R. africana O. Tattersall

- Antennal sympod bearing 1 longest mesial second spine flanked by shorter most mesial spine and much shorter 5–7 lateral spines: carpo-propodus of seventh thoracic endopod composed of 8–10 sub-segments........... R. philippinensis sp. nov.

7 Antennal sympod bearing 2 prominent mesial spines of sub-equal length flanked by 2 short lateral spines................................................................................................... R. brisbanensis Hodge

- Antennal sympod bearing 1 prominent mesial second spine flanked by much shorter most mesial spine and 1–3 short lateral spines................................................................................ R. hastatus sp. nov.

8 Antennal scale distinctly overreaching anterior end of antennular peduncle........................................ 9

- Antennal scale barely reaching or slightly overreaching anterior end of antennular peduncle approximately by length of distal suture............................................................................................. 11

9 Carpo-propodus of seventh thoracic endopod composed of 7 or 8 sub-segments, carpus shorter than entire length of propodus............................................................................... R. terranatalis O. Tattersall

- Carpo-propodus of seventh thoracic endopod composed of 4 sub-segments, carpus distinctly elongated, sub-equal to entire length of propodus................................................................................... 10

10 Telson armed laterally with 14–16 moderately long setae, length of posterior series as long as posterior width of telson............................................................................................... R. longipes Ii

- Telson armed laterally with 9–12 unusually strong setae, length of posterior series longer than posterior width of telson.......................................................................................... R. armiger sp. nov.

11 Telson with marked constriction near apex.......................................... R. constrictus Panampunnayil

- Telson without constriction near apex..................................................................... 12

12 Antennal sympod bearing 5 spines arranged in form of cone, with median spine longest................. R. indicus Pillai

- Antennal sympod bearing 2 or 3 prominent spines flanked by a few much smaller lateral spines...................... 13

13 Antennal sympod bearing 3 prominent graduated spines flanked commonly by 2 small lateral spines.... R. egregius Hansen

- Antennal sympod bearing 2 prominent spines of sub-equal length flanked commonly by 1 or 2 small lateral spines....... 14

14 Telson with marked basal waist......................................................................... 15

- Telson without basal waist or hardly defined, if present....................................................... 21

15 Inner pair of spinose apical telson setae longer than outer pair................................................. 16

- Inner pair of spinose apical telson setae shorter than outer pair................................................ 17

16 Rostrum well advanced, sub-triangular; rudimentary endopods of eighth thoracopods poorly developed in both sexes, not reaching mid-length of basal plate of exopods................................................ R. tattersallae Pillai

- Rostrum obtusely rounded; rudimentary endopods of eighth thoracopods in both sexes moderately developed, extending well beyond mid-length of basal plate of exopod............................................. R. orientalis O. Tattersall

17 Rudimentary endopods of eighth thoracopods in both sexes reaching or extending well beyond distal end of basal plate of exo- pod................................................................................................ 18

- Rudimentary endopods of eighth thoracopods in both sexes falling far short of distal end of basal plate of exopod........ 19

18 Rostrum wide triangular; telson armed laterally with 14 setae; carpo-propodus of seventh thoracic endopod with 3 sub-seg- ments.............................................................................. R. kempi O. Tattersall

- Rostrum obtusely rounded; telson armed laterally with 11 setae; carpo-propodus of seventh thoracic endopod with 4 or 5 sub- segments................................................................... R. anishi Panampunnayil & Biju

19 Carpo-propodus of seventh thoracic endopod with 4 sub-segments............... R. murudana Panammupunnayil & Biju

- Carpo-propodus of seventh thoracic endopod with 5 or 6 sub-segments.......................................... 20

20 Telson armed laterally with 14–19 setae; rostrum wide triangular...................... R. tropicalis Wooldridge & Mees

- Telson armed laterally with 11 or 12 setae; rostrum obtusely rounded.............. R. mumbayensis Panampunnayil & Biju

21 Inner pair of spinose apical telson setae longer than outer pair................................................. 22

- Inner pair of spinose apical telson setae as long as or shorter than outer pair...................................... 23

22 Telson unusually long, posterior end including spinose apical setae extending end of uropodal exopod; rudimentary endopod of male eighth thoracopod poorly developed, reaching utmost to mid-length of basal plate of exopod..................................................................................................... R. longicauda O. Tattersall

- Telson moderate in length, posterior end including spinose apical setae falling far short of end of uropodal exopod; rudimen-

tary endopod of male eighth thoracopod elongated, extending beyond basal plate of exopod........... R. macropsis Pillai 23 Telson armed laterally with fewer than 10 setae on length of distal two-fifths; carpo-propodus of seventh thoracic endopod with 5 sub-segments......................................................... R. vijayai Panampunnayil & Biju

- Telson armed laterally with more than 15 setae on length of distal two-thirds; carpo-propodus of seventh thoracic endopod with 7 or more sub-segments............................................................................... 24

24 Carpo-propodus of seventh thoracic endopod with 7 sub-segments; antennal scale more than 5 times as long as wide....................................................................................... R. mediterraneus Nouvel

- Carpo-propodus of seventh thoracic endopod with 9–11 sub-segments; antennal scale less than 5 times as long as wide............................................................................. R. tartessicus Vilas-Fernández et al.