Glandulotiron hexamatius, 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 : 36-39

Glandulotiron hexamatius sp. nov.

( Figs 19–20 )

Type fixation. Holotype, ♀.—Here designated.

Etymology. Named in Greek hexa (for six) mati (eyes, ‘accessory’).

Material examined. Holotype, ♀, 8.0 mm. Australia, Eastern Bass Strait, Tasmania, 24 km NNE of Eddystone Point, 40˚43.54’S, 148˚32.30’E, 56 m, medium sand, R. Wilson , S-M grab, muddy fine sand, little shell, 14 November 1981, RV Tangaroa , stn BSS163 , NMV J73774 .

Paratypes. Same data as holotype, NMV J73773 (7 specimens) . Same data as holotype, NMV J73776 (1 ♂, illustrated) . Australia, Tasmania, Southern Ocean , 15 km E of Cape Connella, 43˚24.36’S, 147˚32.30’E, 82 m, epibenthic sled, R. Wilson, 22 October 1984, FRV Soela, stn S05/84/64 ( BSS232 ), NMV J73732 (4 specimens) . Australia, Tasmania, Eastern Bass Strait, Flinders Island , 94 km NE of North Point, 38˚53.42’S, 147˚55.06’E, 71 m, medium sand, R. Wilson, 17 November 1981, RV Tangaroa , stn BSS171 , NMV J73752 (2 ♂, 7 ♀) . Australia, Central Bass Strait , 35 km WNW of West Point, Tasmania, 40˚47.4’S, 144˚17.7’E, 99 m, coarse sand, M. Gomon et al., 2 February 1981, FRV Hai Kung, stn BSS125 , NMV J73754 (1 ♂) . Australia, Victoria, Western Bass Strait , 44 km SW of Cape Otway, 39˚06’8’’S, 143˚07’24’’E, 81 m, medium sand, R. Wilson, 21 November 1981, stn BSS 192 , NMV J73759 (1 small ♀) . Australia, Tasmania, Eastern Bass Strait, Flinders Island , 94 km NE of North Point, 38˚53.42’S, 147˚55.06’E, 71 m, medium sand, R. Wilson, 17 November 1981, RV Tangaroa , stn BSS171 NMV J73760 (1 ♂) . Australia, New South Wales, Wattamolla, Bass Point , 34°08’S, 151°08’30”E, 45–50 m, Smith-McIntyre Grab, The Ecology Lab for RMI / Pioneer, Project , January 1990, AM P46799 (1 specimen) . Australia, New South Wales, east of Malabar , 33°58’S, 151°16’E, 32 m, Australian Museum Shelf Benthic Survey, 1973, AM P23997 (5 specimens) . Australia, Central Bass Strait, 94 km NE of North Point, Flinders Island , 38˚53.42’S, 147˚55.06’E, 71 m, medium sand, R. Wilson, 15 November 1981, RV Tangaroa , stn BSS171 , NHMD 916111 (3 ♀) .

Description (female). Head dorsal surface with tiny setules. Rostrum bluntly pointed. Interantennal lobes broad, truncate with subequal rounded corners. Accessory eye composed of 6 ommatidia in crescent.

Mouthparts. Maxilla 1 with 6 short pointed, minuscule serrate apical setal spines and a single more slender serrate one in lateral corner; outer plate with row of 9 setal spines. Mouthparts otherwise normal.

Antenna 1 as long as pereonite 1–6 combined along dorsum, peduncle article 2 about two thirds length of 1, article 3 two thirds length of 2, article 1 with single penicillate seta ventrally in posterior half and two middorsally; flagellum slightly longer than peduncle, of 9 articles, assessory flagellum of 5 articles. Antenna 2 as long as pereonites 1–7 combined along dorsum, peduncular article 4 the longest; flagellum of 7+ articles, several articles with single slender robust seta distally, antenna otherwise sparsely setose.

Coxal plates 1–4 distally fringed with setae of varying length, without brim of fine setules.

Gnathopods 1 and 2 propodus slightly less than half as long as carpus; dactylus with unguis half as long as propodus, nearly straight; basis with long and short anterior and posterior setae; carpus on both with scattered setae on anterior margin, 11–12 groups of unequally long setae along posterior margin. Gnathopod 1 propodus with about 7 short stout, pectinate setae on posterior margin; gnathopod 2 propodus posterior margin with scattered slender setae.

Pereopods 3–4 basis with numerous anterior and posterior small setae; propodus with long, straight seta anterodistally.

Pereopods 5–7 basis with posterodistal rounded projection, pereopod 5 and 6 basis broadest distally, posterior margin straight; pereopod 7 of equal width throughout, with rounded posteroproximal lobe, propodus about half as long as carpus, carpus with groups of robust setae on anterior margin; pereopods 6 and 7 with row of long setae submarginally on medial surface of basis.

Uropod 1 peduncle reaching about 5/6 along peduncle of uropod 2 peduncle, rami of equal length, about 3/4 length of peduncle, reaching to end of rami of uropod 2; both uropods reaching nearly halfway along outer ramus of uropod 3. Uropod 2 outer ramus about 5/6 length of inner ramus. Uropod 3 peduncle about 3/4 length of outer ramus, rami elongate oval, reaching beyond apex of telson, outer ramus basal article with row of 11 robust setae dorsolaterally, and small robust setae ventrolaterally, small second article with 3 dorsal robust setae; inner ramus reaching to 9/10 of basal article of outer ramus, dorsal margin with row of long setae and 3 robust setae, apex with 3 robust setae.

Telson. Reaching 3/5 along outer ramus of uropod 3, length/width 2.5, with row of 4 robust setae, small simple setae and doublet of plumose setae dorsally on each lobe, apices with 1 long and 1 short robust seta.

Male. Similar to female but differing as follows: antenna 1 flagellum article 1 with ventral row of about 20 long aestetascs in apparently single field callynophore; antenna 2 peduncle article 3 dorsally with cover of small setules, flagellum of antenna 2 of 7 articles; basis of gnathopods 1 and 2 much less setose; posterior flange of basis of pereopod 7 slightly broader.

Size. Largest ♀, 8.7 mm. Largest ♂, 7.2 mm.

Distribution. Australia, Bass Strait, 56– 99 m.

Figures

FIGURE 19. Glandulotiron hexamatius gen. et sp. nov. Holotype, ♀, except M, ♂ paratype. clv, head, lateral view; md, mandible; mx1 plp, maxilla 1 palp; tel, telson with internal glands; us, urosome.

FIGURE 20. Glandulotiron hexamatius gen. et sp. nov. Holotype, ♀. cox3, coxal plate 3; gp1, gnathopod 1; gp2, gnathopod 2; p4–7, pereopods 4 to 7.