Colomastix, Grube, 1861

Silvany, Liz & Senna, André R., 2019, Three new species of Colomastix Grube, 1861 (Amphipoda: Colomastigidea) from Todos-os-Santos Bay, northeastern Brazilian coast, with identification keys to Atlantic Ocean species, Zootaxa 4629 (4), pp. 519-554 : 549-550

Key to adult females of Colomastix species from the Atlantic Ocean

1. Inner plate of maxilliped cleft........................................................................... 2

- Inner plate of maxilliped entire.......................................................................... 5

2. Gnathopod 2, dactylus insertion terminal.................................................................. 3

- Gnathopod 2, dactylus insertion subterminal............................................................... 4

3. Telson lateral margins castellated............................................................... C. castellata

- Telson lateral margins smooth................................................................. C. fissilingua

4. Gnathopod 1, propodus with about 5 terminal, distally curved setae; uropod 3, inner ramus expanded.......... C. bastidai

- Gnathopod 1, propodus with 2 terminal, distally curved setae; uropod 3, inner ramus unexpanded.......... C. simplicauda

5. Eyes protruding laterally; antenna 2, lateral of peduncle 3–5 lacking line of small, equally-spaced setae; maxilliped, basal shell expanded as a ventral keel; gnathopod 2, insertion of dactylus subterminal; pleopods 1–3, outer ramus 4-articulate, inner ramus 3-articulate; urosomite 1 elongate; telson linguiform......................................................... 6

- Eyes not protruding laterally; antenna 2, lateral of peduncle 3–5 lined with small, equally-spaced setae; maxilliped, basal shell not expanded as a ventral keel; gnathopod 2, insertion of dactylus terminal; pleopods 1–3, rami with equal number of article (except for Colomastix tubulosa sp. nov.); urosomite not 1 elongate; telson subtriangular or subovate.................. 8

6. Interantennal plate, anterior margin strongly serrate; antennae 1, dorsomedial and ventromedial margins strongly serrate or with small spines; antenna 2, article 3, distomedial process present.................................................. 7

- Interantennal plate, anterior margin smooth, slightly concave; antennae 1, dorsomedial and ventromedial margins smooth; antenna 2, article 3, distomedial process absent................................................. C. halichondriae

7. Interantennal plate, anterior margin with single ventral tooth; antenna 1, dorsomedial and ventromedial margins with small spines; antenna 2, dorsomedial margin with very small spines, ventromedial margins smooth; pereopods 3–7, propodus flexor margin lacking setae, dactylus with nail; pereopod 5, carpus elongated..................... Colomastix marielle sp. nov.

- Interantennal plate, anterior margin lacking ventral tooth; antenna 1, dorsomedial and ventromedial margins strongly serrate; antenna 2, dorsomedial and ventromedial margins strongly serrate; pereopods 3–7, propodus flexor margin with a single seta, dactylus without nail; pereopod 5, carpus not elongated............................................ C. denticornis

8. Uropod 3, inner ramus wedge-shaped, slightly shorter than outer ramus, broadly expanded ventrally, ventral margin densely setose.............................................................................................. 9

- Uropod 3, inner ramus lanceolate or expanded proximally, longer or subequal to outer ramus in length, not expanded ventrally, ventral margin lacking setae........................................................................... 11

9. Rostrum acute or subacute; uropod 1, peduncle subequal to inner ramus in length................................. 10

- Rostrum rounded; uropod 1, peduncle slightly shorter then inner ramus................................. C. falcirama

10. Rostrum subacute; interantennal plate, anterodorsal angle projecting slightly beyond anteroventral angle, forming slight overhang; antenna 2, peduncle article 3 with one large distomedial setae adjacent to a large process; uropod 2, peduncle subequal to inner ramus in length; telson tip slightly truncate................................................... C. bousfieldi

- Rostrum acute; interantennal plate, anterodorsal and anteroventral angles projecting forward subequally; antenna 2, peduncle article 3 with one large distomedial setae, but adjacent process absent; uropod 2, peduncle slightly shorter than inner ramus; telson tip rounded.............................................................................. C. heardi

11. Head length slightly longer than first pereonite (except C. sarae ); pereopods 3–7, propodus flexor margin lacking setae... 12

- Head length subequal to first pereonite; pereopods 3–7, propodus flexor margin with setae (except for C. escobarae )..... 16

12. Head length subequal to first pereon segment; rostrum acute; antenna 1, article 1, dorsomedial margin with 3–4 setae; pleopods 1–3, outer ramus 4-articulate, inner ramus 3-articulate; telson subovate.................................... C. sarae

- Head length slightly longer than first pereonite; rostrum subacute; antenna 1, article 1, dorsomedial margin with 0–2 setae; pleopods 1–3, rami 3 or 4-articulate; telson subtriangular.................................................... 13

13. Uropod 1, peduncle subequal to inner ramus; uropod 3, inner ramus slightly longer than peduncle; telson lateral margins castellated.............................................................................................. 14

- Uropod 1, peduncle longer than inner ramus; uropod 3, rami subequal in length; telson lateral margins smooth.......... 15

14. Interantennal plate, anterior margin concave; antenna 1, article 1, dorsomedial margin lacking seta; antenna 2, peduncle 3 with 1 elongate seta and 1 shorter seta adjacent to a very strong, inwardly curved distomedial process, tip of setae not extending tip of process; oostegite narrowly subovate, tip of setae curled; pleopods 1–3, rami 4-articulate; telson lateral margins strongly castellated, tip not bilobed, rounded............................................................... C. camura

- Interantenal plate, anterior margin straight; antenna 1, article 1, dorsomedial margin with 1 seta; antenna 2, peduncle 3 with single, large distomedial seta adjacent to small, broad process, tip of setae extending well beyond tip of process; oostegite subovate, tip of setae not curled; pleopods 1–3, rami 3-articulate; telson lateral margins weakly castellated, tip faintly bilobed, slightly truncate.......................................................................... C. cornuticauda

15. Interantennal plate, anteroventral angle extending slightly beyond anterodorsal angle; antenna 2, peduncle 3 with single, large distomedial seta adjacent to small process, tip of setae extending well beyond tip of process; gnathopod 5, dactylus tip pleated; uropod 1, peduncle slightly longer than inner ramus, inner ramus slightly longer than outer; uropod 3, inner ramus slightly expanded proximally............................................................ Colomastix iemanja sp. nov.

- Interantennal plate, anterodorsal and anteroventral angles projecting forward subequally; antenna 2, peduncle 3 with 1 elongate seta and 1 shorter seta adjacent to distomedial process, tip of elongate seta and process extending forward subequally; gnathopod 5, dactylus tip not pleated; uropod 1, peduncle subequal to rami in length, rami subequal in length; uropod 3, inner ramus lanceolate................................................................................... C. gibbosa

16. Interantennal plate, anteroventral and anterodorsal angles projecting forward subequally; antenna 2, peduncle article 3 with one distomedial seta; oostegites, tip of setae not curled; uropod 2, rami subequal in length.............................. 17

- Interantennal plate, anteroventral angle projecting forward than anterodorsal angle; antenna 2, peduncle article 3 with two distomedial setae; oostegites, tip of setae curled (except for C. tridentata ); uropod 2, inner ramus longer than outer ramus (except for C. tridentata )................................................................................ 18

17. Interantennal plate, anterior margin straight to slightly concave; antenna 2, peduncle article 3, with small distomedial process; oostegites subovate; pereopods 3–7, propodus flexor margin with 5–14 short, curled setae; uropod 1, peduncle slightly longer than inner ramus, inner ramus slightly longer than outer ramus; telson lateral margins smooth, upturned proximally.................................................................................................... C. irciniae

- Interantennal plate, anterior margin concave; antenna 2, peduncle article 3, lacking small distomedial process; oostegites narrowly subovate; pereopods 3–7, propodus flexor margin with 2–5 short, stout setae; uropod 1, peduncle much longer than rami, rami subequal in length; telson lateral margins castellated, not upturned proximally......................... C. janicea

18. Interantennal plate, anteroventral angle projecting slightly beyond anterodorsal angle; antenna 1, peduncle article 1, dorsomedial margin with 4–5 stout setae; uropod 2, rami subequal in length.................................... C. tridentata

- Interantennal plate, anteroventral angle projecting far beyond anterodorsal angle; antenna 1, peduncle article 1, dorsomedial margin with 2–4 stout setae; uropod 2, inner ramus longer than outer ramus..................................... 19

19. Gnathopod 2, dactylus with pleated apex; pereopods 3–7, propodus flexor margin lacking setae, dactylus with nail; uropod 1, inner ramus apex differentiated, with two distal cusps and minute setae................................. C. escobarae

- Gnathopod 2, dactylus lacking pleated apex; pereopods 3–7, propodus flexor margin with 1–4 setae, dactylus lacking nail; uropod 1, inner ramus lanceolate, simple................................................................. 20

20. Interantennal plate, anterior margin concave; antenna 2, peduncle article 3, with small distomedial process; pleopods 1–3, outer ramus 4-articulate, inner ramus 3-articulate; uropod 1, inner ramus longer than outer ramus; telson, lateral margins smooth............................................................................... Colomastix tubulosa sp. nov.

- Interantennal plate, anterior margin straight; antenna 2, peduncle article 3, lacking small distomedial process; pleopods 1–3, rami 4-articulate; uropod 1, rami subequal in length; telson, lateral margin castellated...................... C. trispinosa