Lepesubchela christinae, Johansen & Vader, 2015

Johansen, Per-Otto & Vader, Wim, 2015, New and little known species of Lepechinella (Crustacea, Amphipoda, Lepechinellidae) and an allied new genus Lepesubchela from the North Atlantic, European Journal of Taxonomy 127, pp. 1-35 : 28-32

Lepesubchela christinae sp. nov.

urn:lsid:zoobank.org:act:BB597D14-331E-46F2-8C31-52D6BF7977EB

Figs 17–19

Diagnosis

Body with teeth on peraeon segments 2–7 and pleon segments 1–4. Urosome segments 2–3 fused. Head without rostrum and postantennal corners, no eyes. Mandible palp present, 3-articulate. Gnathopods 1–2 subchelate; peraeopods 6–7 also clearly subchelate. Uropods with rami well-developed, with many spines.

Etymology

The species is named after POJ’s youngest daughter.

Material examined

The holotype was collected 4 Jun.1983 at station 83.06.4.1, in the North Atlantic Ocean , southwest of the Faroes and northeast of Rockall (at position 59 o 40.4’N, 09 o 20.6’W). The specimen was sampled at a depth of 1414 meter where the in situ temperature was measured to 4.5 o C. No further material was found. The holotype is deposited in the collections of Zoological Museum in Bergen, Norway under registration no. ZMBN 99136 .

Description

Holotype

4 mm, immature (no external gender characteristics observed).

BODY. Sparsely covered with setae that are attached to crown-like pegs. Peraeon segment 1 dorsally smooth; peraeon segments 2–7 and pleon segments 1–4 each with one dorsal tooth. Urosome segments 2–3 fused. Coxal plates 1–5 all biacuminate, decreasing in length posteriorly.

HEAD. Subequal to peraeon segments 1+2, no distinct rostrum or postantennal corners; eyes absent or at least indistinct in alcohol, an invagination at the basis of antenna 2. Antenna 1, peduncle article 1 broader than article 2 and 3; peduncle article 2 is 2x as long as article 1; peduncle article 3 is 0.5x art 1; accessory flagellum is 1-articulate with three apical setae; flagellum slightly longer than peduncle articles 1–3 combined; flagellum 12-articulate.Antenna 2 is 1.5x antenna 1. Antenna 2, peduncle articles 4 and 5 long, subequal; flagellum shorter than article 5; flagellum 6-articulate.

MOUTHPARTS. Upper lip circular; lower lip inner lobe 3/4 of outer; mandible with lacinia mobilis as long as incisor, both armed with denticles; 7–8 accessory setae; molar elevated, trapezoid with rounded angles. Palp 3-articulate; article 2 the longest, 1.5x article 3 and 4.5x article 1; article 3 tapering, with 3 apical setae. Maxilla 1, inner plate narrow with 2 long apical setae; outer plate with 8 serrate spine teeth; palp 2-articulate; article 2 slightly obliquely truncate, with 4 blunt and 1 apical long spine. Maxilla 2, inner plate shorter and narrower than outer plate; inner plate with 1 strong plumose and a few simple setae; outer plate with 12 medial and apical setae. Maxilliped, inner plate apically with 3 blunt spines and a few

setae, inner plate 0.6x outer plate; outer plate with 5 slender apical spine teeth of varying length; palp 4-articulate, article 2 as long as articles 3+4 combined.

PERAEON. Gills smooth, long and narrow. Gnathopod 1, subchelate and quite stout (for a lepechinellid); coxal plate 1 asymmetrically bifid with anterior process twice as long as posterior, both with a serrate edge; basis tapering proximally, slightly longer than merus and carpus combined; propodus oval, with four groups of medial setae; palm slightly longer than posterior margin, with marginal spines and a cluster of spines delimiting the palmar corner. Gnathopod 2 longer and more slender than gnathopod 1; gnathopod 2 subchelate; coxal plate 2 asymmetrically bifid with acute lobes; merus short; carpus slightly longer than propodus; propodus oblong; palm straight, oblique, slightly longer than posterior border, with many and strong marginal spines. Coxal plate 3 higher than broad, asymmetrically bifid, with anterior lobe longest; merus longer than carpus and propodus; dactyl lanceolate and as long as carpus and propodus combined. Coxal plate 4 higher than broad, asymmetrically bifid; merus longer than carpus and propodus; merus subequal to lanceolate dactyl. Coxal plate 5 broader than high, biacuminate; carpus subequal to basis and longer than merus; dactylus lanceolate, as long as propodus. Peraeopod 6 clearly subchelate; coxal plate 6 rectangular with posterodistal corner acute; merus shorter than carpus; basis subequal to carpus; propodus and dactylus stout and subequal in length, both with strong blunt marginal spines. Peraeopod 7 clearly subchelate; coxal plate 7 lemon-shaped with posterodistal corner acute; basis subequal to carpus; merus shorter than carpus; propodus and dactylus stout and subequal in length, with strong blunt marginal spines.

PLEON. Epimeral plates 1–3 each with a strong acute posterodistal tooth. Uropod 1 peduncle armed with two distal and several lateral spines; peduncle subequal in length to outer ramus; inner ramus 0.8x outer ramus; both peduncle and rami heavily spinose. Urosome segments 2–3 fused. Uropod 2 peduncle subequal to outer ramus; outer ramus 0.8x inner; inner ramus with strong marginal spines. Uropod 3 peduncle short and wide, 1/3 to 1/4 of rami; rami with marginal spines and apical setae. Telson cleft to about half of total length, halves widely gaping, with long apical setae.

Remarks

Lepesubchela christinae gen. et sp. nov. is characterized by setae attached to crown-shaped pegs on the body; Rostrum and dorsal teeth on peraeon segment 1 is absent. The species has an invagination at the basis of antenna 2 and is lacking postantennal corners as in Lepechinelloides karii Thurston, 1980 . Coxal plates 1–5 biacuminate. Antenna 2 peduncle article 5 longer than flagellum. Posterodistal angle of epimeral plates 1–3 without sinus and strongly acute. Gnathopods 1 and 2, peraeopods 6 and 7 subchelate and armed with strong teeth. The mandible molar is special and looks like a trapezoid with spine-like margins. Lower lip of L. christinae gen. et sp. nov. resembles the lower lip of L. skarphedini and upper lip, maxilliped, maxilla 1 and 2 are similar to several Lepechinella species.

The family Lepechinellidae consists of a single speciose genus, Lepechinella , and a number of small genera, that in most cases vary in only one or two apomorphies. The new genus Lepesubchela similarly is primarily distinguished by a single strong autapomorphy, the prehensile posterior peraeopods, although also the morphology of the head is deviant. Whether these different autapomorphies really delimit independent evolutionary lines, can only be decided on the base of a cladistic analysis preferably including molecular data.

Figures

Fig. 17. Lepesubchela christinae gen. et sp. nov., holotype, immature. A. Habitus. B. Setae attached to crown-shaped peg. C. Left Ep1. D–E. Left and right Ep2. F. Left Ep3. G. Right Gn1. H. Left Gn2.

Fig. 18. Lepesubchela christinae gen. et sp. nov., holotype, immature. A–B. A1 with accessory flagellum. C. A2. D. Right P3 with gill. E. Left Mxp. F. Left Mx1. G. Left Mx2. H. Lower lip. I. Upper lip. J. Right mandible.

Fig. 19. Lepesubchela christinae gen. et sp. nov., holotype, immature. A. Left P4. B. Tooth of peraeon segment 5. C. Left P5. D. Left P6. E. Right P7. F. Left U1. G. Right U2. H. U3. I. Telson.