Siriella brevicaudata, Paulson, 1875

Daneliya, Mikhail, Price, W. Wayne & Heard, Richard W., 2018, Revision of the Siriella brevicaudata species group (Crustacea: Mysida: Mysidae) from the West Indo-Pacific, European Journal of Taxonomy 426, pp. 1-80 : 69-71

Key to the species of the Siriella brevicaudata group

1. Last (terminal) pair of posterolateral spiniform setae of telson less than twice as long as subterminal. Uropodal endopod with more than nine spiniform setae, occupying entire or almost entire inner margin of ramus.............................................................................................................2

– Last (terminal) pair of posterolateral spiniform setae of telson three times as long as subterminal. Uropodal endopod with three spiniform setae, occupying proximal part of the ramus ....................... ...................................................................................................................... S. gibbosa Ledoyer, 1970

2. Telson apically with slight emargination..........................................................................................3 – Telson apically straight or convex....................................................................................................4

3. Telson with 4 to 7 posterolateral spiniform setae, with last pair 0.4–0.5 times as long as telson ............................................................................................................ S. brevicaudata Paulson, 1875

– Telson with 9 to 13 posterolateral spiniform setae, with last pair 0.2 times as long as telson ............. ................................................................................................................................. S. occulta sp. nov.

4. Anterodorsal margin of carapace angular, apically rounded, with straight or slightly concave lateral sides. Terminal spiniform seta on medial margin of uropodal endopod reaching apex of ramus .................................................................................................................................................5

– Anterodorsal margin of carapace smoothly or nearly smoothly rounded. Terminal spiniform seta on medial margin of uropodal endopod not reaching apex of ramus...................................7

5. Telson rather long and narrow, 2.35–2.5 times as long as wide (at maximum anterior width); its last (terminal) pair of posterolateral spiniform setae 0.07–0.08 times as long as telson. Male carapace with cephalic tubercle .............................................................................. S. bassi sp. nov.

– Telson <2.1 times as long as wide; its last (terminal) pair of posterolateral spiniform setae 0.11–0.14 times as long as telson. Male carapace without cephalic tubercle...............................6

6. Carapace without cephalic tubercle. Terminal pair of posterolateral spiniform setae of telson longer than subterminal pair in male ......................................................... S. spinula Panampunnayil, 1995

– Female carapace with cephalic tubercle. Terminal pair of posterolateral spiniform setae of telson shorter than or as long as subterminal pair in both sexes ................ S. vincenti W.M. Tattersall, 1927

7. Telson as long as or longer than last abdominal somite. Last (terminal) pair of posterolateral spiniform setae of telson <0.13 times as long as telson.........................................................................8

– Telson shorter than last abdominal somite. Last (terminal) pair of posterolateral spiniform setae of telson> 0.13 times as long as telson............................................................................................9

8. Last three to six pairs of posterolateral spiniform setae of telson nearly equal in length. Anterior spine of labrum very short, barely visible, <0.1 times as long as rest of labrum. Uropodal endopod with 10 to 13 medial spiniform setae ............................. S. hanseni W.M. Tattersall, 1922

– Last pairs of posterolateral spiniform setae of telson gradually increasing in length, with terminal pair clearly longer than subterminal. Anterior spine of labrum rather long, 0.25–0.3 times as long as rest of labrum. Uropodal endopod with 17 or 18 medial spiniform setae ...... S. talbotae sp. nov.

9. Cephalic tubercle absent. Telson with 5 or 6 anterolateral spiniform setae. Uropodal exopod 3.6–3.7 times as long as wide ........................................................................... S. lingvura Ii, 1964

– Cephalic tubercle present. Telson with 3 or 4 anterolateral spiniform setae. Uropodal exopod 3.9–4.2 times as long as wide........................................................................................................10

10. Last (terminal) pair of posterolateral spiniform setae of telson 0.25 times as long as telson. Last terminal and subterminal spiniform setae of telson about twice as long as preceding posterolateral. Uropodal exopod proximal segment 1.4–1.5 times as long as distal segment .................... ...................................................................................................................... S. lacertilis Talbot, 2009

– Last (terminal) pair of posterolateral spiniform setae of telson 0.13–0.19 times as long as telson. Last terminal and subterminal spiniform setae of telson 1.2–1.4 times as long as preceding posterolateral. Uropodal exopod proximal segment 1.7–1.9 times as long as distal segment.............11

11. Terminal pair of posterolateral spiniform setae of telson about as long as subterminal pair and 0.13–0.14 times as long as telson. Labrum spine short, but well-established, about 0.2 times as long as rest of labrum ....................................................................................... S. muranoi sp. nov.

– Terminal pair of posterolateral spiniform setae of telson clearly longer than subterminal pair and 0.18–0.19 times as long as telson. Labrum spine very short, barely visible, <0.1 times as long as rest of labrum ................................................................................. S. tabaniocula sp. nov.

Additional observations