Stenothoe himyara, 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 : 2338-2343

Stenothoe himyara n. sp.

( Figures 14–17 ; Table 1)

Holotype

Male 2 mm, Port Sudan, Flamingo Bay, corals and short algae + epiphytes, 11.12. 1970, U. Schiecke coll. 1 slide MVRCr 7614 .

Additional material

Same locality as above: two females dissected on slide MVRCr 7615 ; 14 females 1.7–2 mm, five juv. 1.5 mm in alcohol. All deposited at MVRCr.

Type locality

Port Sudan, Red Sea.

Etymology

Many living beings found in the Red Sea receive the specific name ‘erythraeus, -a, -um’ (classical Greek for ‘red’), stressing the colour of the earth or sandstone in the region. But there is also another explanation, going back to the population of the Himyares living there, allegedly also meaning ‘the red ones’. The epithet is used as an adjective.

Diagnosis

Length 1.5–2 mm. Male Cx 1, 2 and 3 without serration on distoposterior margin. U 3 male ramus art 2 proximal half about as wide as long or wider, then abruptly narrowing and bluntly ending like a thumb.

Description

Length 1.5–2 mm. Head. Antennae: A 1 three times longer than head, about as long as head + peraeonites and clearly shorter than A 2. A 1 flagellum about 14 arts, A 2 flagellum about 11 arts.

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

Peraeon. Coxae: Cx 2 in both sexes longer than wide, anteriorly rounded; Cx 3 rectangular, more than twice as long as wide, Cx 4 smooth, shield-like and trapezium-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 twice as long as Gn 1 propodus, in adult males propodus ratio l:b somewhat more than 2, distally near dactylus insertion no teeth or incisions, neither posterior margin nor dactylus inner margin beset with dense long setae; carpus triangular, shorter than wide; merus longer than wide, distally acute, posterior margin smooth.

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

Pleon. Uropods: U 1 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 and the claw- or dactylus-like art 2. U 3 male peduncle is shorter than ramus, with one distal spine; art 1 is subequal art 2 in length and has two distal spines. The last article of the ramus U 3 shows a very peculiar shape being circularly rounded proximally and abruptly narrowed in about half of the length, with the distal half of about one third of the width, strongly sculptured and thumb-like rounded ending. Telson: triangular, with two pairs of spines.

Remarks

This quite small species has an astonishingly similar U 3 to the Atlantic new species S. clavetta , seemingly a useful convergent structure within the S. gallensis group (may be for fixing the body somewhere?). Otherwise, there are important differences, such as the length (S.c. twice as big), the Gn 2 in males (without special teeth or incisions in S.h.) and A 2 <A 1 in S.h., vs subequal in S.c.

Distribution

Red Sea.

Figures

Figure 14. Stenothoe himyara n. sp., Red Sea. A 1, 2 = antennae; Mx 1, 2 = first and second maxillae; Md = mandible; Mxp = maxilliped; Gn 2 = second gnathopod female.

Figure 15. Stenothoe himyara n. sp., Red Sea. Gn 1, 2 male small and enlarged.

Figure 16. Stenothoe himyara n. sp. Red Sea. P 3–7 = peraeopods 3–7.

Figure 17. Stenothoe himyara n. sp., Red Sea. Ep 3 = third epimeral plate. Us = urosome of male and female. U1–3 = uropods 1–3; T = telson.