Stenothoe andamanensis, 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 : 2326-2330

Stenothoe andamanensis n. sp.

( Figures 6–8 ; Table 1)

Stenothoe gallensis? Ledoyer, 1986: 973–74 , fig. 384

Holotype

Male 2 mm, harbour of Havelok , Andaman Islands, Bay of Bengal; coralligène, 1–8 m depth; coll. Ulrich Schiecke 22. XII.1978, sample 13; slide MVRCr 7672 .

Additional material

Two males 2 mm, two ovigerous females 2 mm, same locality; slides MVRCr 7673, 7674.

Type locality

Andaman Islands, Indian Ocean.

Etymology

The specific epithet is built as an adjective from the locality of Andaman Islands.

Diagnosis

Length 2 mm. Gn 2 male palm with many long setae. Gn 2 female propodus shallow excavate. Cx 2 male quadrate and excavate. P 6, 7 posteriorly straight or excavate. U 3 male peduncle <ramus, peduncle subequal ramus article 1 subequal article 2.

Description

Length 2 mm.

Head. Eyes medium, round. Mxp IP well visible, OP absent. Mx 1 palp with two arts. Mx 2 plates riding. A 1 ≥ A 2, in female A 1 flagellum with nine arts, A 2 with seven arts.

Peraeon. Gn 1 basis slender, naked; merus not reaching end of carpus, length of propodus subequal to carpus + merus, marginally and distally with long and flexible plus short and stiff setae; carpus triangular; propodus with clear medial palmar corner of about 150°, with remarkable group of defining setae; length of palm subequal to that of remaining hind margin.

Cx 2 male about as long as wide, posteriorly excavate. Gn 2 merus posterior margin smooth, distally acutely ending and often surpassing carpus. Propodus in male with straight and densely setose palm, distally with two humps; dactylus setose. Peraeopods: P 5 basis l: b = 3; merus posterodistally not much lengthened or widened; with nearly rectangular bases on P 6–7 in males, hind margin less widened than in females, without posterodistal lobe.

Pleon. U 1 richly spinose, rami subequal; U 2 rami clearly different; U 3 peduncle shorter than ramus, ramus art 1 with 1–2 robust spine(s), ramus art 2 straight and not upwards bent, medially thickened and with strong grooves. Telson proximally with a pair of spines, distally some setae.

Ovigerous female. Gn 2 merus distally rounded, propodus with only a few setae, palm with characteristic shallow excavation; dactylus naked. U 3 second art of ramus straight, without grooves and not thickened, distally scarcely upwards bent.

Remarks

This species belongs to the S. gallensis group, and differs in some easily visible morphological details from Stenothoe gallensis from Sri Lanka: first of all in the body length (only half as long), then in the Gn 2 of the females (shallow excavation on palm of propodus) and in the shape of U 3 (last article not upwards bent or ‘geniculate’, but straight and distally thickened).

The description of ‘ Stenothoe gallensis’ by Ledoyer (1986, p. 973–74, fig. 384) matches well with the present species, but Gn 2 female does not show the excavation on the palm of propodus and U 3 male is not thickened distally. Both could depend on immature material.

Distribution

Andaman Islands, Indian Ocean.

Figures

Figure 6. Stenothoe andamanensis n. sp., Andaman Islands: Mx 1, 2 = first and second maxilla; Mxp = maxilliped; A 1, 2 = antenna 1, 2; Gn 1, 2 = gnathopod 1, 2 male.

Figure 7. Stenothoe andamanensis n. sp., Andaman Islands: Gn 1, 2 juv. male; Gn 2 female = gnathopod; P 6, 7 female resp. P 5, 6, 7 male = peraeopods.

Figure 8. Stenothoe andamanensis n. sp., Andaman Islands: P 7 = peraeopod 7; U 1, 2, 3 male resp. female = uropods; T = telson.