Glandulotiron, Just, 2022

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 : 25-28

publication ID	https://doi.org/ 10.11646/zootaxa.5139.1.1
publication LSID	lsid:zoobank.org:pub:145CB6F5-2EA8-40B0-9CCA-3E942AA4A5B9
DOI	https://doi.org/10.5281/zenodo.6827619
persistent identifier	https://treatment.plazi.org/id/03BF0417-FFC9-FF0A-FF1A-8FA5E2D6FAF5
treatment provided by	Plazi
scientific name	Glandulotiron
status	gen. nov.

Treatment

Glandulotiron View in CoL gen. nov.

Diagnosis. Tironin synopiids with mandible palp article 2 curved. Interantennal head lobe of varying truncate to rounded lobe form. Coxal plates 1–4 of subsimilar shape, 1 and 4 slightly shorter than 2 and 3, anterior and posterior margins nearly parallel, apex broadly rounded, coxal plates 5 and 6 strongly posterolobate, much wider than plates 1–4 and posterior lobe somewhat deeper than first 4 plates, coxal plate 7 short, much wider than deep. Gnathopods 1 and 2 with straight basis about as long as succeeding 3 articles, carpus slender, elongate, dactylus with unguis slightly curved about half as long as propodus. Gnathopod 1 propodus with row of pectinate robust setae on posterior margin. Gnathopod 2 propodus posterior margin with scattered slender setae. Pereopods 3 and 4 basis straight, about as long as next 3 articles combined. Pereopods 3–7 propodus short, dactylus with unguis short, subby, (see Fig. 1a View FIGURE 1 , Fig.15 p View FIGURE 15 3 View FIGURE 3 ). Urosomites 1–3 with posterior dorsal spine and long thin setae dorsally. Uropods and telson with rows of glands.

Etymology. The name refers to the glandulous urosome and telson in combination with the basic name of the group.

Type species. Glandulotiron pilocaputis View in CoL sp. nov. — Here designated.

Two forms. The new genus Glandulotiron View in CoL appears to come in two forms. In species from western and southern Africa the second, short article of the outer ramus of uropod 3 has a single strong apical robust seta ( Fig. 38 View FIGURE 38 up3), whereas species from Australasia and Vietnam carry 3 robust setae normally of increasing length dorsal-wise ( Fig. 31 View FIGURE 31 us). There is a large gap in distribution between these forms as nothing is known from eastern Africa, a large stretch of western Africa, and the entire northern Indian Ocean. More material from these areas, needs to be studied before two species groups could be formally assessed.

The urosome glands. Species in Glandulotiron View in CoL gen. nov. (and one species in Pseudotiron View in CoL , see below) possess a unique character in uropod peduncles and adjacent parts of urosomites as well as the telson lobes which have rows of elongate glands opening ventrolaterally on the limbs. The glands are often very distinctive ( Fig. 14 View FIGURE 14 up2 ped, Fig. 36 View FIGURE 36 tel), but time and preservation may render them nearly impossible to verify, although rows of dark blotches or the row of tiny openings are often indicative. Glands for production of amphipod silk are found in pereopods 3 and 4 in various families in the infraorder Corophiida , but the shape and position of the glands found here appear to be previously unreported, and their function is unexplained.

Description of mouthparts (based on the type species, see Fig. 16 View FIGURE 16 ). Upper lip in lateral view distally inward curved, outside of curve with dense cover of long setules, inside apex blunt with tiny setules. Mandible molar prominent, triturative; setal row of numerous sharply pointed setae; incisors and laciniae subequally dentate; palp of 3 articles, article 2 curved, much longer than subequal 1 and 3, article 2 with a few to several long setae, article 3 with 2 apical long setae. Lower lip outer lobes widely separate, angular pointed mediodistally with cover of fine setules; inner lobes prominent, broadly rounded with similar setules on distal margin. Maxilla 1 palp of 2 articles, club-shaped, article 2 much longer than 1, widest in distal third, with lateral cover of fine setae and 6–7 apical robust setae of varying shape; outer plate with row of 9–10 pointed robust setae; inner plate rounded with row of simple setae along medial margin. Maxilla 2 both lobes distally rounded, outer lobe about 1/4 longer than inner lobe, with row of setae along mediodistal margin, inner lobe about as broad as outer, with row of setae along medial and apical margins and oblique row of setae on medial surface. Maxilliped palp of 4 articles, article 2 about as long as 1 and 3 combined, 4 at most half as long as 3, terminal claw as long as or longer than article 5, outer plate reaching to apex of palp article 2, apically with a few long setae and an apical to medial row of spatulate setae of decreasing length; inner plate rectangular, reaching half way along outer plate, with a few spatulate and simple setae on apical margin and row of submarginal setae.

In description of species of Glandulotiron below, mouthparts are considered as normal if they match the above description; deviations are mentioned.

Key to species of Glandulotiron View in CoL gen. nov.

(See also Fig. 12 View FIGURE 12 comparison of heads, and Fig. 13 View FIGURE 13 comparison of urosomes)

1. Gnathopod 2 with robust setae on basis or merus............................................................. 2

- Gnathopod 2 with simple, pectinate or plumose setae only..................................................... 3

2. Gnathopod 2 basis with anterodistal row of strong, robust setae................................. G. spinipes View in CoL sp. nov.

- Gnathopod 2 merus with strong robust setae on posterior margin............................. G. meruspinosus View in CoL sp. nov.

3. Head without projecting interantennal lobes, lower corner of interantennal margin rounded........................... 4

- Head with projecting interantennal lobes....................................................................5

4. Interantennal head margin sinuous, lower angle rectangularly rounded, urosomite 3 dorsal tooth normal, backward pointing................................................................................... G. salsevisio View in CoL sp. nov.

- Interantennal head margin straight, lower angle broadly rounded, urosomite 3 dorsal tooth upward recurving................................................................................................ G. curvispinus View in CoL sp. nov.

5. Interantennal head lobe rounded without upper and lower corners............................................... 6

- Interantennal head lobes with upper and lower rounded corners................................................. 7

6. Gnathopod 2 ischium, merus and carpus with dense rows of strongly plumose setae on posterior margin; uropod 3 outer ramus ventrally with dense felt of setules........................................................ G. griffithsi View in CoL sp. nov.

- Gnathopod 2 with simple setae; uropod 3 outer ramus ventrally naked......................... G. aotearoensis View in CoL sp. nov.

7. Interantennal lobes vertically straight between soft upper curve and rectangular lower corner......... G. postremus View in CoL sp. nov.

- Interantennal lobes with subequal upper and lower rounded corners............................................. 8

8. Interantennal head lobes with distinct mid-concavity......................................... G. concavus View in CoL sp. nov.

- Interantennal head lobes truncate or slightly convex.......................................................... 9

9. Head dorsally with long thin setae....................................................... G. pilocaputis View in CoL sp. nov.

- Head without long dorsal setae.......................................................................... 10

10. Uropod 3 outer ramus with ≥ 10 dorsal robust setae......................................................... 11

- Uropod 3 outer ramus with ≤ 8 dorsal robust setae.......................................................... 13

11. Pereopod 7 basis with large angular posteroproximal projecting lobe; uropod 3 outer ramus with 14–15 dorsal robust setae; telson with 5 robust setae and simple setae on each lobe.................................. G. intermedius ( Reid, 1951) View in CoL

- Pereopod 7 posteroproximal lobe rounded, not angular....................................................... 12

12. Pereopod 7 basis longer than wide, of equal width throughout, with posterior proximal and distal rounded, not angular, projections; telson with 4 robust setae and small simple setae on each lobe............................ G. hexamatius View in CoL sp. nov.

- Pereopod 7 basis as long as wide, with posterior proximal and distal short projections; telson with 5–6 robust setae and simple setae on each lobe............................................................... G. australis ( Stebbing, 1908) View in CoL

13. Pereopod 7 merus with 3–4 long robust setae on posterior and anterior margin, and numerous short and long setae on anterior margin............................................................................................. 14

- Pereopod 7 merus with single posterodistal robust seta and 1–3 smaller robust setae on anterior margin...................................................................................................... G. septimus View in CoL sp. nov.

14. Rostrum short, broadly rounded, about as broad as long; antenna 1 accessory flagellum of 2+ articles; basis of pereopod 7 of equal width proximally and distally....................................................... G. bassianus View in CoL sp. nov.

- Rostrum narrow, acute, downward pointed (according to Dang & Le, fig. 72); antenna 1 accessory flagellum of 3+ articles; basis of pereopod 7 slightly widest and more rounded proximally.................. G. quadrioculatus ( Dang & Le, 2012) View in CoL