Stenothoe clavetta, Krapp-Schickel, 2015

Krapp-Schickel, Traudl, 2015, Minute but constant morphological differences within members of Stenothoidae: the Stenothoe gallensis group with four new members, keys to Stenothoe worldwide, a new species of Parametopa and Sudanea n. gen. (Crustacea: Amphipoda), Journal of Natural History 49 (37), pp. 2309-2377 : 2330-2338

Stenothoe clavetta n. sp.

( Figures 9–13 ; Table 1)

Stenothoe valida Kunkel 1910: 16–19 , fig. 5

Holotype

Male 3 mm, Sandys Parish, Fort Scaur, Great Sound , 15 feet depth. 2/VIII/1991, coll. W. Rose; in alcohol. YPM IZ 20473 .

Additional material

Alcohol material (all material coming from Bermuda and deposited at YPM; if not otherwise noted, collected by Michael Gable):

IZ 20381 one spec. St. George’ s Parish, off Natural Arches Beach, from algae 8 m

depth, 6.I.1987, coll. A. Baldinger + E. Lazo-Wasem. IZ 20382 one fem. 3 mm. North Rock, from broken sea whip encrusted with algae.

8 m depth, 6.II.1987, coll. A. Baldinger. IZ 20383 four spec. off Bermuda, North Rock, from algal scrapings, 9 m depth. 2/VI/ 1987, coll. A. Baldinger.

IZ 20384: one spec., St. George’ s Parish, off Natural Arches Beach., from bottom sediment (sand) 8 m depth, 6.I. 1987.

IZ 20386: six fem.+ juv. Harrington Sound, ‘Shark Hole’, green algae. 25.V.1987.

IZ 20387: 22 fem. and juv. North Rock, coll. Eric Lazo-Wasem 8.II. 1987; algal scrapings and debris.

IZ 20389 two spec. Hamilton Parish, Harrington Sound, ‘Shark Hole’, from attached invertebrates and algae. 25/V/1987.

IZ 20390 eight spec. Hamilton Parish, Harrington Sound, ‘Shark Hole’ in Jania (alga); 25/V/1987. Coll. A. Baldinger.

IZ 20391 five juv. Hamilton Parish, Harrington Sound , behind Bermuda Aquarium, from Agaricia , oyster shell and debris. 2/VI/1987 .

IZ 20462 63 fem. and juv.; Hamilton Parish, Shelly Bay, off Promontory NNW of bay. 3/VI/1985.

IZ 20463 10 males, fem. juv. 2.5–3.5 mm. Hamilton Parish, Shelly Bay, off Promontory NNW of bay. 3/VI/1985 .

IZ 20464 one male 3 mm Hamilton Parish, Shelly Bay, 3/VI/1985.

IZ 20465 two spec. Hamilton Parish, Shelly Bay, 3/VI/1985.

IZ 20466 45 fem. and juv. Hamilton Parish, Shelly Bay, 3/VI/1985.

IZ 20467 eight males, fem. and juv., 2.5–3 mm. Hamilton Parish, Shelly Bay, 3/VI/1985.

IZ 20468 one male 3 mm; Hamilton Parish, Harrington Sound, SharkHole. 3/VI/1985.

IZ 20469 12 spec., Hamilton Parish, Harrington Sound , Bermuda Aquarium, entrance to Harrington Sound across from Bermuda Aquarium. 17/VIII/1988. Coll. E. Lazo- Wasem and J. Hamilton. two slides male 3 mm, one slide female 2.5 mm .

IZ 20470 25 fem. ov. and juv. Hamilton Parish, Harrington Sound, Bermuda Aquarium, entrance to Harrington Sound across from Bermuda Aquarium. 17/ VI/1988, coll. E. Lazo-Wasem and J. Hamilton .

IZ 20471 60 males, ov. females and juv., beautiful sample: St. George’ s Parish, underneath Long Bird Causeway. S side and under. 20/VI/1988, coll. E. Lazo- Wasem.

IZ 20472 five fem. + juv., Southampton Parish, off Pompano Beach Club. 2 m depth, 21/VI/1988, coll. E. Lazo-Wasem.

IZ 20473 14 spec., Sandy’ s Parish, Fort Scaur, Great Sound, 15 feet depth. 2/VIII/ 1991, coll. W. Rose.

IZ 20474 45 males, ov. fem. and juv. 3–3.5 mm; St. George’ s Parish, Whalebone Bay, railroad pilings between Whalebone Bay and Coney Island. 10 feet fepth, 3/VI/ 1991, coll. A. Elston and W. Rose. One slide fem. 3 mm.

IZ 20475 56 males, fem. ov. and juv., but bad material. St. George’ s Parish, Whalebone Bay, railroad pilings between Whalebone Bay and Voney Island. 10 feet depth. 3/VI/1991, coll. A. Elston and W. Rose.

IZ 500047 two juv. 2 mm, one juv. 1.5 mm, 27.V. 1989, Shelly Beach, subtidal algae.

IZ 500233 two juv. 2 mm, 1.5 mm, 30.V. 1989, algae on Boilers.

Etymology

The specific name alludes to the shape of the third uropod of the male, similar to a little club, pin or bludgeon; the Latin word ‘clavetta’ is used as noun in apposition.

Diagnosis

Length 2.5–3.5 mm. Male Cx 1, 2 and 3 with fine serration on distoposterior margin. U 3 male ramus art 2 the proximal half about as wide as long, then abruptly narrowing and bluntly ending.

Description

Length. 2.5–3.5 mm.

Head. Antenna 1 three times longer than head, about as long as head + peraeonites and subequal to A 2. Dorsal smooth. A 1 flagellum about 18 arts, A 2 flagellum about 15 arts.

Mouthparts: Md with lacking palp; Mx 2 plates in riding position; Mxp long and narrow, IP and OP short.

Peraeon. Coxae. Cx 1 in adult male and female distally with some incisions, Cx 2, 3 on posterodistal corner irregularly finely dentate; Cx 2 in male about twice as long as wide, anteriorly shorter and rounded; Cx 3 rectangular, more than twice as long as wide, Cx 4 smooth, shield-like, trapeze-shaped, wider than long.

Gnathopods: Gn 1 propodus twice as long as wide, carpus triangular, merus on posterior margin beset with spines. Gn 2 female similar to Gn 1, merus less prominent, without spines and distally acute; propodus with smooth palm and strong defining spines on palmar corner. Gn 2 male propodus up to three times as long as Gn 1 propodus, in adult males propodus ratio l:b about 3, distally narrowing and near dactylus insertion 1–2 teeth, posterior margin as well as dactylus inner margin densely beset with long setae; carpus triangular, shorter than wide; merus longer than wide, posterior margin smooth, with short setae.

Cx 3 with fine serration on distoposterior margin.

Peraeopods: P 5 basis linear. P 6, 7 basis ovoid and subequal, about twice as long as wide, posterior margin with incisions; merus posterodistal corner somwhat widened and lengthened, reaching about one third of carpus.

Pleon. Uropods: U 1 naked peduncle (vs S. gallensis peduncle with spines) with distal spur, rami somewhat unequal, with few spines. U 2 similar to U 1, but without spur and shorter; U 3 in female peduncle with three strong spines, about the same length as ramus article 1, while the claw- or dactylus-like art 2 is shorter. U 3 male peduncle is longer than ramus (vs in S. gallensis subequal to ramus), with 3–4 spines, art 1 is longer than art 2 and has two distal spines. The last article of the ramus has a very peculiar shape, being rounded and thickened proximally and abruptly narrowed in about half of the length (vs S. gallensis , whereas art 2 is sculptured, but not abruptly narrowed), with the distal half about one third of the width, strongly sculptured and finger-like rounded ending. Telson: triangular, with three pairs of spines.

Distribution

Bermuda, Atlantic Ocean.

Remarks

There is no doubt that Kunkel described the here found new species, under the name of Stenothoe valida ; his illustration of U 3 fits perfectly in its unusually thickened and abruptly narrowing last article. Barnard (1955, p. 5) had already surmised that this species is a new one. However, in the text, Kunkel writes that the second article of the ramus is longer than the first one (which is not the case in our material, and the opposite is illustrated in his fig. 5), and it is not clear what he illustrated with ‘ep 3’; it may be the second coxa. Kunkel even mentions the serration on some coxae (‘ventral margin very finely serrate’), a unique character in the ‘ gallensis group’, to which it clearly belongs.

Figures

Figure 9. Stenothoe clavetta n. sp., Bermuda: habitus male; Mx 1, 2 = maxilla 1, 2; Md = mandible; Mxp = maxilliped.

Figure 10. Stenothoe clavetta n. sp., Bermuda: Gn 1, 2 = gnathopod 1, 2 in male and female; Gn 1ʹ, 2 ‘ and ‘‘ = gnathopod 1, 2 enlarged.

Figure 11. Stenothoe clavetta n. sp., Bermuda: Gn 2 male = second gnathopod male; Cx 2 male = second coxa in male with serration; P 3 male = peraeopod 3 in male; Cx 3 male = third coxa in male with serration; P 4 = peraeopod 4.

Figure 12. Stenothoe clavetta n. sp., Bermuda: P 5, 6, 7 = peraeopod 5, 6, 7; Us = urosome in male; U 1, 2, 3 = uropod 1, 2, 3; T = telson.

Figure 13. Stenothoe clavetta n. sp., Bermuda: Us = urosome of male and female; U 1, 2, 3 = uropod 1, 2, 3.