Synopiidae, Dana, 1853

Just, Jean, 2022, Tirons of the world: a review of ‘ tironid’ amphipods, description of new genera and species, and establishment of a new subfamily Tironinae Stebbing, 1906 stat. nov. (Crustacea, Synopiidae), Zootaxa 5139 (1), pp. 1-89 : 6

New key to genera of Synopiidae

(amended from Lörz & Coleman 2013)

1. Coxal plate 1 strongly reduced, hidden behind plate 2; coxal plate 4 distally expanded without posterior concavity, larger than 2 and 3; coxal plates 5–7 much longer than deep, not lobate; dactylus and unguis lacking on mandible palp, gnathopod 1 and gnathopod 2; unguis lacking on pereopods 3–7; pereopod 5 basis dominating 6 and 7........... Cardenio Stebbing, 1888 *

- Coxal plate 1 subequal to 2 and 3; coxal plate 4 shorter than 3, with more or less strong posterior concavity; coxal plates 5 and 6 posterolobate, often strongly; dactylus and unguis present on mandible palp and all gnathopods and pereopods; pereopod 7 basis dominating 5 and 6 to some degree (often a large degree)................................................. 2

2. Pereopods 3–7 short, dactylus/unguis stubby ( Fig. 1a ), or pre-stubby ( Fig. 1b ) short, with curved counter-seta on dactylus........................................................................ Tironinae new subfamily (key below)

- Pereopods 3–7 elongate with simple, elongate dactylus/unguis................................................. 3

3. Gnathopods simple without definite corner or defining robust seta............................................... 4

- One or both gnathopods subchelate, with definite corner or defining robust seta.................................... 6

4. Telson cleft......................................................................................... 5

- Telson entire................................................................ Telsosynopia G. Karaman, 1986

5. Head rounded with downturned rostrum eyes and accessory eyes present, article 2 of mandible palp with strongly expanded length and width, propodus of gnathopod 1 nearly as broad as long, uropod 1 reaching beyond uropod 2, uropod 3 outer ramus with slender article 2, telson short, reaching just beyond peduncle of uropod 3...................... Synopia Dana, 1852

- Head elongate, projecting to blunt apex, rostrum a tiny non-projecting vestigial slit, propodus of gnathopod 1 slender elongate, uropod 1 not reaching to tip of uropod 2, uropod 2 reaching just beyond peduncle of uropod 3, uropod 3 outer ramus with tiny article 2, telson long, reaching to tip of uropod 3 rami.................................... Synopiidae incertae sedis *

6. Palm of gnathopods transverse or nearly so................................................................. 7

- Palm of gnathopods oblique............................................................................. 8

7. Coxae 3–4 pelagont**.................................................................. Syrrhoe Goes, 1866

- Coxae 3–4 not pelagont....................................................... Garosyrrhoe J.L. Barnard, 1964

8. Mandibular molar, usually triturative and generally columnar or subcolumnar, but occasionally smooth and minutely setulose, body of mandible stout not extraordinarily bulky or subglobular, palp relatively strong.............................. 9

- Mandibular molar very large and smooth, minutely setulose, molar completely dominating mandible, body of mandible bulky, subglobular, together with molar often dwarfing palp (exceptions in Ileraustroe and Jeddo )......................... 10

9. Telson very long and narrow, entire (female) or slightly cleft (male)................... Priscosyrrhoe J.L. Barnard, 1972

- Telson short and broad, cleft about halfway...................................... Austrosyrrhoe K.H. Barnard, 1925

10. Coxae 3–4 pelagont.................................................................................. 11

- Coxae 3–4 not pelagont............................................................................... 12

11. Mandibular palp absent............................................................. Jeddo J.L. Barnard, 1962

- Mandibular palp present............................................................................... 13

12. Antenna 1 with apicodorsal tooth on article 1, telson entire or apical cleft vestigial............ Bruzeliopsis Chevreux, 1911

- Antenna 1 lacking apicodorsal tooth on article 1, telson cleft............................ Ileraustroe J.L. Barnard, 1972

13. Telson cleft one third or more........................................................................... 14

- Telson entire or bearing minute incision.................................................................. 15

14. Gnathopod 1–2 propodus palms with 1–2 serrate robust setae, coxa 1 narrow and tapering distally.................................................................................................. Latacunga J.L. Barnard, 1972

- Gnathopod 1–2 propodus palms with 1–2 simple spines, coxa 1 not tapering.................. Syrrhoites G.O. Sars, 1893

15. Gnathopod 1–2 propodus palms with 1–2 serrate robust setae................................. Bruzelia Boeck, 1871

- Gnathopod 1–2 propodus palms with about 4 simple robust setae..................... Stephobruzelia J.L. Barnard, 1969

* Provisionally for 3 species previously in Pseudotiron (see Introduction).

** Coxal plate 3 larger than 4, surrounding the latter in an L-shape ( Barnard & Karaman 1991, p. 806 Appendix 111 Glossary of Special Terms).

Figures

FIGURE 1. Representative habitus illustrations of tironin genera. Tiron spiniferus (from Sars, 1895 pl. 140, ♀ 8 mm); Pseudotiron miratus sp. nov. (this paper, ♀, 4.5 mm); Tironella pervicax comb. nov. (from J.L. Barnard, 1967 fig. 84, ♂ 4.7 mm); Glandulotiron pilocaputis sp. nov. (this paper, ♀, 6.3 mm); Metatiron tropakis (from J.L. Barnard, 1967 fig. 45, ♀, 4.9 mm); Minitiron bellairsi comb. nov. (from Just, 1981 fig. 1, ♀ 2.4 mm). a and b, dactylus and unguis of pereopods 3–7: a, stubby; b, pre-stubby.