Ringanui toonuiiti, Fenwick, Graham D., 2006

Fenwick, Graham D., 2006, Ringanui, a new genus of stygobitic amphipod from New Zealand (Amphipoda: Gammaridea: Paraleptamphopidae), Zootaxa 1148, pp. 1-25 : 15-23

Ringanui toonuiiti n. sp.

( Figs 7–11 )

Calliopius subterraneus .—? Chilton, 1884: 89; Chilton, 1894: 234 –242, pl. 22, figs 1–16, pl. 23, figs 1–9 (part, male only).

Paraleptamphopus subterraneus .— Chilton, 1924: 276 (part, male only).

Material examined

Holotype: adult Ψ, 13.2 mm long, NMNZ CR.10010 (wet and 7 slides); Burnham, Canterbury, 43º37.17´S, 172º18.86´E, coll. G.D. Fenwick, 3 Feb 1999, taken in net from Well 1, 18 m depth. Allotype: ɗ 10.7 mm long, NMNZ CR.10011 (wet), Templeton, Canterbury, 43º33.11´S, 172º26.38´E, coll. G.D. Fenwick, 28 Jan 1986, among cages in well. Paratypes: Templeton, Canterbury, 43º33.11´S, 172º26.38´E: 1 ɗ, NMNZ CR.10012, coll. G.D. Fenwick, 28 Jan 1986, taken in net, c. 20 m depth; 1 Ψ, 12.6 mm long, AM P.68199 (wet), coll. L. Sinton, 19 Aug. 1982, net sample from Well 2; 2 females, 10.8, 11.7 mm long, NIWA 3443, P­1431, coll. L. Sinton, 5 Aug. 1982, net sample from Well 11, 20 m depth; 1 Ψ, NMNZ CR7724, coll. G.D. Fenwick, 12 Mar. 1986, among cages in Well 11; Bailey’s Rd, East Eyreton, Canterbury, 43º23.93´S, 172º34.14´E: 1 Ψ, 11.0 mm long, NZAC Ph 133 (wet & 1 slide), coll. J. McBurney & L. Brown, 24 May 1973, pump sample from open well, 5.1 m deep, temperature 13.5 ºC.

Additional material: Templeton, Canterbury, 43º 33.11´S, 172º 26.38´E: 1 indet., coll. L. Sinton, 3 Sept 1982, in Well 11, c. 20 m depth [ NIWA GW15­2]; 1 indet., coll. G.D. Fenwick, 17 Sept 1986, among cages in Well 2 [ NIWA GW 29­4]. Burnham, Canterbury, 43º 37.17´S, 172º18.86´E: 1 Ψ, 3 juveniles, coll. L. Sinton, 19 July 1982, net sample from Well 12 [ NIWA GW 21­1]; 1 Ψ, coll. L. Sinton, 5 Aug 1982, taken in net from Well 10, 20 m depth [ NIWA GW 41­2]; 1 Ψ, 3 juveniles, coll. L. Sinton, 5 Aug. 1982, in net from Well 13 [ NIWA GW 42­1]; 1 ɗ, coll. G.D. Fenwick, 3 Feb. 1999, net sample from Well 1, 18 m depth [ NIWA GW 51­1]; 1 Ψ, 1 ɗ, coll. G.D. Fenwick, 3 Feb 1999, in net samples from Well 2, c. 20 m depth [ NIWA GW 53­1]; 1 indet., coll. G.D. Fenwick, 9 Feb 1999, taken in net from well in forest, 18 m depth [ NIWA GW95­1]; Harewood, Canterbury, 43º 28.4´S, 172º 32.6´E: 1 indet. (poor condition), NZAC Ph 57, coll. G. Kuschel, 4 July 1972, in pump sample from well 10.4 m deep; Orari, Canterbury, 44º07.7´S, 171º20.0´E: 1 Ψ, NZAC Ph 115­a, coll. G. Kuschel & J. McBurney, 22 March 1973, pumped from open well, 4.8 m deep, water temperate 13º C.

Diagnosis

Size up to 13.2 mm long; maxilla 1 inner plate with 5–6 large, plumose SS medially; maxilla 2 outer plate with several (<10) setules distolaterally; maxilliped outer plate just exceeding distal end of palp article 1 and not reaching midpoint of article 2; maxilliped palp article 1 lateral margin with 2–5 SS, article 2 lateral margin with 3–4 SS distolaterally, article 4 with 2–3 setules laterally and 4–6 medially; gnathopod 1 coxa 1 broader than deep, anterior margin weakly concave, straight distally; gnathopod 1 article 6 posterior margin discontinuous with palm, largest defining RS less than half as long as dactyl and shorter than article 6 width; gnathopod 2 article 6 subequal in length to gnathopod 1 article 6, gnathopod 2 palm defined by 4–6 RS, 1–2 of which are long; pereopod 5 coxa posterior lobe subequal to anterior lobe; pereopod 6 coxa anterior lobe distinct, but reduced; pereopods 6–7 article 2 tapered to obtuse, subquadrate lobe posterodistally; pereopods 5–7 dactyl posterior margins with 2–5 setules; pleopod rami subequal in length, of 12–15 articles; uropod 1 peduncle with 4 RS proximolaterally, outer ramus just shorter than inner; uropod 2 with 2 RS laterally; uropod 3 rami 1.5 times longer than peduncle, margins with paired RS; telson untapered distally, weakly emarginate, lobes rounded.

Description (holotype)

The same as R. koonuiroa except for the following characters. Head lateral cephalic lobes subrectangular. Pleon dorsally with sparse short SS; urosome dorsally with sparse, short SS.

Antenna 1 calceoli present on peduncle article 2; peduncle 0.4 x flagellum length. Antenna 2 0.7 x as long as antenna 1; peduncle article 4 1.2 x length of 5; flagellum 1.4 x length of peduncle articles 4–5.

Mandible palp article 1 short, wider than long, article 3 strongly curved and falciform, 0.8–0.9 x length of article 2, palp setal formula: 10 D2­setae, 25 D3­setae, 3 E3­setae; incisor large, 6 strong cusps; lacinia mobilis well developed, toothed. Lower lip inner lobes weakly developed. Maxilla 1 palp article 2 3 x longer than wide, linear, 4 RS distally, 2 SS laterodistally; outer plate distal margin bearing 11 dentate RS, inner margin with group of SS distally; inner plate subovate, 1.3 x longer than wide, 4 plumose SS, inserted medially. Maxilla 2 outer plate length 2 x width, distal margin oblique, armed with 9 large SS, medial margin with long setules; inner plate 2 x longer than wide, distal margin oblique, discontinuous with medial margin, bearing 15 simple SS, inner margin with 3 marginal setae, and 1 simple SS submarginally. Maxilliped inner plate distal margin with 3 RS and 2 SS, medial margin with 3 SS; outer plate not reaching mid point of palp article 2, mediodistal corner quadrate, 1.6–1.7 x longer than wide, with a row of 4 RS, decreasing in length medially, changing to 2 palmate RS medially, inner margin discontinuous with distal margin, with 8 SS and 2 RS; palp article 1 5 distolateral SS, 0 SS mediodistally, article 2 1.3 x longer than 1, 0 SS distolaterally, 4 setae along lateral margin, article 3 2 x longer than wide, article 4 0.6 x length of article 3 (excluding distal nail or spine), 3.5 x longer than basal width, medial margin straight, with 6 SS, outer margin bearing 3 SS, nail present, 0.2–0.3 x article length.

Coxal gills present on pereonites 2–7; surface weakly ridged. Oostegites present on pereonites 2–5, subtriangular, 1.3– 2 x longer than wide, most extending extending to end of second articles or extending beyond second articles, with 2–5, very short SS; on margins. Gnathopod 1 coxa 0.8 x deeper than long, extending to 0.3 x length of article 2, anterior margin concave, anterodistal corner produced into broad lobe, with marginal SS posteroventrally only; article 2 4 x longer than wide, slightly constricted proximally; article 3 0.2–0.3 x length of 2; article 4 0.8 x length of 3; article 5 short, 0.3–0.4 x length of article 2, subtriangular, 1.3 x as long as wide, posterodistal margin with 8–10 SS; article 6 very large, 1.2 x length of article 2, 3.4 x length of article 5, 1.7 x longer than wide, posterior margin (proximal to palm) 0.2–0.3 x length of article length, bearing several SS; palm strongly oblique, 25 degrees to article 6 axis, straight or convex, finely ridged, palm defined by 12 RS, simple, longest defining spine 0.2 x article 6 length; dactyl with 13 posterior setules. Gnathopod 2 subchelate, large, as long as, and as stout as gnathopod 1; coxa anterior margin straight; article 2 3.8–3.9 x longer than wide; article 3 elongate, 0.4 x length of 2, 0.6 x length of article 5; article 4 1 x length of 3; article 5 elongate, 0.6 x length of article 2, subtriangular, 2.5 x as long as wide, anteriodistal corner with 1 SS, with 30–40 SS posteriodistally; article 6 large, subovate, narrowed distally, 0.9 x length of article 2, 1.5 x length of article 5, 2 x longer than wide; palm strongly oblique, 25 degrees to article axis, convex, finely corrugated, defined by 5 bifid RS, largest 0.2 x length of article 6; dactyl slender pointed, posterior margin with 8 setules, 0 facial setules subterminally.

Pereopod 3 coxa length (depth) 1.9 x width; article 2 0.9– 1 x as long as coxa, 5 SS posteriorly; article 3 0.1 x as long as article 2; article 4 0.6 x length of article 2; article 5 0.6–0.7 x length of article 4; articles 4–6 moderately setose; article 6 1.3 x length of article 5, 6 RS, and 1 SS along posterior margin, 0 RS, and 8 SS anteriorly; dactyl stout, slightly curved, 0.3 x length of article 6, posterior margin simple, tip simple. Pereopod 4 coxa 1.8 x depth of coxa 5, extending to 0.5 x length of article 2, 1.4–1.5 x deeper than wide, posterior margin weakly excavate proximally; articles 2–7 similar to pereopod 3 in proportions and setation of articles. Pereopod 5 coxa 1.5 x wider than deep; article 2 expanded, 1.5 longer than wide, posterior margin finely toothed, posteriodistally produced into short, angular obtuse lobe, anterior margin with several RS; article 4 0.5–0.6 x length of article 2; article 5 1.2 x as long as article 4; article 6 1.3 x length of article 5; articles 4–6 with numerous RS; dactyl posterior margin with 4–5 fine setules. Pereopods 6–7 similar to pereopod 5 in article shape and setation; successively longer. Pereopod 6 coxa posterior lobe with 8 SS and 0 RS; article 2 anterior margin with many RS, posterior margin almost straight, serrate, posterodistally produced to overhang article 3 for about 0.4 of its length, lobe angular, obtuse. Pereopod 7 coxa posterior lobe naked; article 2 subovate, anterior margin with many RS, posterodistally produced to overhang article 3 for about 0.6 of its length, lobe angular, obtuse.

Epimeron 1 posterior margin convex, naked; posterodistal corner subquadrate or acute; naked. Epimeron 2 posterior margin weakly convex, naked. Epimeron 3 posterior margin weakly convex, naked; posteroventral corner subquadrate. Pleopod 1 peduncle 1.6–1.7 x longer than wide, with pair of coupling hooks only; inner ramus with 15 articles, article 1 1.6 x longer than wide, 3 simple SS medially, plus pair of distal plumose SS; outer ramus with 14 articles, article 1 1.4 x longer than wide, 3 simple SS, mediodistally, and 9 plumose SS laterally, plus pair of plumose SS distally, outer ramus 0.7–0.8 x as long as inner. Pleopods 2–3 similar in structure and size to pleopod 1. Pleopod 2 outer ramus 15 articulate, 0.8 x as long as inner; inner ramus with 14 articles. Pleopod 3 outer ramus 14 articulate, 0.8 x as long as inner; inner ramus with 12 articles.

Uropod 1 peduncle with 3 RS mediodorsally, 4 RS dorsolaterally, terminal dorsolateral RS smaller in size than others; inner ramus 0.8 x length of peduncle, with 4 RS laterally, 4 medially, and 4 distally; outer ramus 0.7 x length of inner, with 5 RS laterally, 5 medially, and 4 distal RS. Uropod 2 peduncle slender, 2.5 x longer than wide, with 6 RS mediodorsally, 3 RS dorsolaterally; inner ramus 0.8–0.9 x length of peduncle, with 3 RS laterally, 1 medially, and 4 distally; outer ramus 0.7 x length of inner, with 2 RS laterally, 3 medially, and 3 distal RS. Uropod 3 extending as far as uropods 1–2; peduncle stout, 1.4 x longer than wide, with 3 RS mediodorsally, 1 RS dorsolaterally; inner ramus 1.2 x length of outer ramus with 7 RS laterally, and 6 medially, terminally stout, 2 subterminal SS and, 0 RS terminally; outer ramus 1.4 x length of peduncle, with 5 RS laterally and 4 medially, 1 subterminal slender seta and 0 RS terminally. Telson subrectangular, untapered, lateral margins straight, 1 x as long as wide, emarginate, 0.1 of its length, lobes distally rounded, with 1 setules subterminally on each lobe, and 2–3 setules laterally.

Va r i a t i o n

A few additional characters not included in the above description merit noting. Calceoli occur on peduncle articles 2–3 of antenna 1 in all specimens examined, although they were not apparent on article 3 in the holotype. Each calceolus arises from a raised hump on the peduncle articles. The upper lip is ovate (distal half only illustrated for holotype) and there is no division between labium and epistome. Some asymmetry is apparent in the mandibles with the left incisor having 6 cusps and the right 5. Similar asymmetry occurs on the lacinia mobili, which have 4 cusps on the left and 3 on the right. Chilton (1894) showed a distinct medial notch in one of the outer lobes of the lower lip and a similar notch was apparent in one of the specimens examined here. Very little asymmetry was apparent in maxilla 1 other than slight differences in palp article 2 width and the stoutness of apical robust setae. The inner plate of maxilla 2 has an oblique, submarginal row of 5–6 plumose setae in all specimens, although these were not readily visible in the holotype.

Gnathopod 1 article 2 is consistently kinked proximally. The dactyl tips of both gnathopods close into crater­like depressions surrounded by robust setae at the proximal ends of their respective palms. Also, the palm is complex with an apparently fine, crenulated knife­edge structure opposing the dactyl along much of the palm. Just proximal to the palm, article 6 is produced into a massive, blunt cusp­like structure (see Chilton 1984: pl. 23, figs 1, 2), but this, like the fine palmar cutting edge, is not apparent in some perspectives. Examination of the few juveniles of this species in collections showed that shape of article 6 and the length of largest defining spines changes little with development.

A small gill was found on coxa 7 in several specimens, but was absent from others. It is not known whether this gill is always present, but was dislodged in some specimens, or whether this small gill is variable in its presence. The lateral margin of the uropod 3 inner ramus had robust setae paired with long, plumose slender setae in some specimens, but this, also, appeared to be a variable character. The telson also seems to vary between specimens, with the emargination slightly deeper than that illustrated for some specimens.

Etymology

The name toonuiiti is derived from Maori toonui (thumb) and iti (little) and refers to the smaller robust seta defining the proximal end of the gnathopod 1 palm, which is characteristic of this species.

Distribution

Canterbury: Eyreton, Harewood, Templeton, Burnham, Orari.

Remarks

As noted above, Chilton’s 1882b “male” differed appreciably from the 1894 male in the morphology of both gnathopods, suggesting the possibility of two species. New material collected since 1972 enabled this to be investigated more carefully, as outlined above, and produced clear evidence that Chilton’s 1882b “male” Calliope subterranea belongs to a different species to his 1894 “male” Calliopius subterraneus . Chilton (1894) appeared to place substantial weight on the structure of gnathopod 1, believing that the 1882 “male” was a juvenile of the 1894 type. Reasons for this are unclear, but he certainly had very few specimens (1894: 236 “I have seen only about half a dozen males altogether”) of Ringanui , with perhaps no more than one specimen of his 1882b “male” ( R. koonuiroa ).

Figures

FIGURE 7. Ringanui toonuiiti holotype Ψ, 13.2 mm long: whole animal (top), antenna 1, 2.

FIGURE 8. Ringanui toonuiiti holotype Ψ, 13.2 mm long: mouthparts.

FIGURE 9. Ringanui toonuiiti holotype Ψ, 13.2 mm long: gnathopods 1, 2.

FIGURE 10. Ringanui toonuiiti holotype Ψ, 13.2 mm long: pereopods 3 – 6.

FIGURE 11. Ringanui toonuiiti holotype Ψ, 13.2 mm long: pereopod 7, pleopods 1 – 3, uropods 1 – 3, telson.