Leucothoe acanthopus Schellenberg, 1928

Kristine N. White & Traudl Krapp-Schickel, 2017, Red Sea Leucothoidae (Crustacea: Amphipoda) including new and re-described species, European Journal of Taxonomy 324, pp. 1-40 : 5-8

Leucothoe acanthopus Schellenberg, 1928

Figs 1–2

Leucothoe acanthopus Schellenberg, 1928: 637 –638, fig. 1 (re-description).

Leucothoe acanthopus – Ruffo 1969: 11.

Diagnosis

Head anterior margin rounded. Maxilla 1 palp 1-articulate, margins constricted. Gnathopod 1 carpus curved; dactylus talon-like. Gnathopod 2 carpus reaching 0.4 times propodus length; propodus palm smooth; dactylus distally tapered and very thin. Pereopods 5–7 bases very narrowly expanded.

Material examined

Neotype

RED SEA: ♂, 3.3 mm, Suez Canal, 1924, E. Bannwarth leg. (MNHB-21542a).

Additional material examined

RED SEA: ♂, 2.9 mm, Suez Canal, 1924, E. Bannwarth leg. (MNHB-21542b) (original type material).

Redescription

Male

LENGTH. 3.3 mm.

HEAD. Anterior margin rounded, anterodistal margin evenly rounded, distal margin straight; ventral cephalic keel anterior margin transverse, anteroventral margin rounded, ventral margin straight; eyes present with many ommatidia, round. Antenna 1 length 0.2 times body length, flagellum 3-articulate, peduncle article 1 less than 2 times as wide as article 2, accessory flagellum present, 1-articulate.Antenna 2 length 0.2 times body length, shorter than antenna 1, flagellum 3-articulate. Mandibular palp ratio of articles 1–3 1.0:2.8:1.5, article 2 with 1 distal seta, article 3 bare, left and right mandibles and upper lip lost in dissection. Lower lip inner lobes fused, setose; outer lobes with large gape, anterior margins setose. Maxilla 1 palp 1-articulate, margins constricted, with 3 distal setae; outer plate with 2 distal robust setae and 7 distal setae. Maxilla 2 inner and outer plates each with 3 distal setae. Maxilliped inner plates distal margin rounded with v-shaped indentation, with several small robust setae; outer plate inner margin smooth, reaching 1.2 times palp article 1, with simple marginal seta; palp article 4 subequal in length with article 3, distally acute.

PErEON. Coxae 1–4 relative widths: 1.0: 1.3: 1.4: 1.6. Gnathopod 1 coxa smooth, bare, anterodistal margin produced, rounded, distal margin rounded, posterior margin excavate; basis slightly inflated, anterior and posterior margins bare; ischium bare; carpus curved, distal length 7.0 times width, proximal margin smooth; propodus straight, palm smooth with 2 small distal setae; dactylus smooth, talon-like, reaching 0.5 times propodus length. Gnathopod 2 coxa broader than long, subequal to coxa 3, smooth, bare, anterior margin rounded, anterodistally rounded, distal margin rounded, posterior margin slightly excavate; basis straight, anterior and posterior margins bare; carpus 0.4 times propodus length, curved, distally tapered, anterior margin smooth; propodus with 1 mediofacial setal row reaching 0.6 times propodus length, posterior margin smooth, palm convex, smooth; dactylus curved, reaching 0.6 times propodus length, proximal margin smooth, bare, anterior margin distally tapered, acute. Pereopod 3 coxa length 0.9 times width, anterodistal corner overriding distal face of coxa 2, smooth, anterior margin rounded, distal margin rounded, posterior margin slightly excavate. Pereopod 4 coxa smooth, anterior margin tapered, distal margin slightly produced, posterior margin tapered. Pereopods 5–7 bases widthlength ratios 1: 1.9, 1: 2.0, 1: 1.9, posterior margins smooth, bare.

PLEON. Epimera 1–3 bare, epimeron 3 posteroventral corner rounded. Uropods 1–3 relative lengths 1.0: 0.6: 0.7. Uropod 1 peduncle length 1.1 times inner ramus length, outer ramus 0.9 times inner ramus length. Uropod 2 peduncle length 0.8 times inner ramus length, outer ramus 0.8 times inner ramus length. Uropod 3 peduncle subequal in length with inner ramus, outer ramus 0.8 times inner ramus length. Uropod 1 inner and outer rami and uropods 2–3 outer ramus with robust setae, uropods 1–3 inner margins of inner and outer rami lined with fine setae. Telson 1.9 times longer than wide, apex tridentate.

Female (sexually dimorphic characters) Unknown.

Distribution

Red Sea: Suez Canal ( Schellenberg 1928; present study), Dahlak Archipelago ( Ruffo 1969).

Depth range

Unknown.

Remarks

In the text about the single specimen of 3.8 mm from the DahlakArchipel off Eritrea, Ruffo (1969) stresses the only difference to the original description is a lanceolate-acuminate telson tip instead of a truncate one, but this is already illustrated in Schellenberg (1928). Leucothoe acanthopus shares characters such as the uni-articulate maxilla 1 palp and short gnathopod 1 dactylus with the new generic-level clade documented in White & Reimer (2012). The relationships of these species need further examination to determine if they should be placed in a different genus. The host for this species is unknown.

Figures

Fig. 1. Leucothoe acanthopus Schellenberg, 1928, neotype, ♂, length 3.3 mm (MNHB- 21542 a).

Fig. 2. Leucothoe acanthopus Schellenberg, 1928, neotype, ♂, length 3.3 mm (MNHB- 21542 a).