Selvacaprella jimenoi, Guerra-García & Tato & Moreira, 2018

Guerra-García, José M., Tato, Ramiro & Moreira, Juan, 2018, Caprellidae (Crustacea: Peracarida: Amphipoda) from deep-sea waters off Galicia (NW Iberian Peninsula) with the description of a new genus and three new species, Zootaxa 4532 (2), pp. 151-202 : 183-190

Selvacaprella jimenoi sp. nov.

( Figs. 24–29 )

Type material. Holotype male, 5.7 mm (used for drawings of lateral and dorsal view, antennae, gnathopods, pereopods 3–7, abdomen and mouthparts, except for the maxilliped which was in poor condition and it was figured from male AT-1000) (vial with 70% ethanol and two slides, mouthparts dissected) ( MHNUSC 10101 ); SELVA 2008 , DRN-15-2, 24 July 2008, 43°56.478’N, 008°54.199’W, 933 m, muddy bottom.

Paratype “a” female 4.8 mm (used for drawings of lateral view, gnathopod 2 and abdomen) (vial with 70% ethanol, mouthparts not dissected) ( MHNUSC 10102 ) ; SELVA 2008 , DRN-15-1, 23 July 2008, 43°58.356’N, 008°52.149’W, 1064 m, gravelly mud.

Paratypes “b” (1 male, not dissected) and “c” (1 juvenile, not dissected, used for lateral view figure), ( MHNUSC 10103 ) ; SELVA 2008 , DRN-15-1, 23 July 2008, 43°58.356’N, 008°52.149’W, 1064 m, gravelly mud.

Additional material examined. 1 male (dissected), 1 female (premature, used for lateral view figures and dissected), 1 juvenile, DIVA-Artabria I 2002, AT-1000, 0 9 September 2002, 43°57.248’N, 008°54.133’W, 1132 m, stones and gravel. Specimens kept in first author’s personal collection.

Diagnosis. Eyes present, although ommatidia not distinguishable. Head and pereonites dorsally smooth, although provided with abundant setae and very tiny tubercles. Anterolateral projections present on pereopod 2, 3 and 4 in males, and absent in females (only very short antelateral projections on pereonite 2). Gnathopod 1 with two grasping spines. Basis of gnathopod 2 as long as pereonite 2. Pereopod 3 and 4 uni-articulate. Pereopod 5 (morphologically different to pereopod 6 and 7) five-articulate, distal article reduce to a very small cone (tabication between two distal articles not totally complete). Molar of the mandibles fully developed. Mandibular palp distal article with a setal formula 1-x- 1, being x=2 or 3. Maxilla 1 outer lobe carrying five spines. Maxilliped palp third article without distal projection. Abdomen with one pair of vestigial appendages.

Etymology. The species is dedicated to our colleague and friend Dr. Antonio Jimeno Fernández, for his valuable contribution to the knowledge of amphipods from the Iberian Peninsula.

Description. Holotype male (5.7 mm)

Lateral view ( Fig. 24 ). Head lacking projections, eyes present but ommatidia not distinguishable. Pereonite 1 fused with head, suture present, clearly marked. Head and pereonite 1 smooth. Pereonite 2 with large anteroateral projections near the coxae. Pereonites 3 and 4 provided with two anterolateral projections proximally. Pereonites 2–6 with numerous dorsal setae and tiny tubercles. Pereonite 5 the longest. Pereonite 7 the shortest.

Gills ( Fig. 24 ). Present at middle of pereonites 3–4, elongate, length about 4 times width.

Mouthparts ( Fig. 26 ). Mandibles with molar; three-articulate palp; distal article of palp with a setal formula 1- x- 1, being x=2 (left mandible) and x=3 (right mandible), medial article provided with a single setae; left mandible with incisor and lacinia mobilis five-dentate, followed by two accessory blades; incisor of right mandible fivedentate, lacinia mobilis looking like a blade, followed by three more blades; no sign of molar flake. Upper lip without setae, with rectangular lobes. Lower lip without setae; inner lobes oval. Maxilla 1 outer lobe carrying five spines, palp two-articulate, distal article with four apical spines and one medial seta. Maxilla 2 inner lobe small, shorter than outer lobe, both with four apical setae. Maxilliped (figured and described from male AT-1000) inner plate small and rectangular, about 1/3 of outer plate in length, carrying two setae, one of them plumose; outer plate oval, with five setae; palp four-articulate, scarcely setose, third article lacking distal projection, distal article (dactylus) not curved.

Antennae ( Figs. 24 and 27 ). Peduncle of antenna 1 of the same length that flagellum, provided with setae, some of them plumose; second article the longest; flagellum 6-articulate. Antenna 2 longer than peduncle of antenna 1; proximal peduncular article with a well developed acute gland cone distally; swimming setae absent; flagellum two-articulate.

Gnathopods ( Figs. 24 and 27 ). Gnathopod 1 basis as long as ischium, merus and carpus combined; grasping margin of propodus smooth; two proximal grasping spines, dactylus bifid distally. Gnathopod 2 inserted on the anterior end of pereonite 2; basis as long as pereonite 2, without distal projection; ischium small rectangular; merus rounded; carpus short and triangular; propodus of gnathopod 2 with a proximal grasping spine followed by Unotch; dactylus smooth and elongate.

Pereopods ( Figs. 24 and 28 ). Pereopod 3 and 4 uni-articulate, elongate provide by three distal plumose setae. Pereopod 5 attached to the middle of pereonite, elongate and provided with long setae, morphologically different to pereopod 6 and 7, five-articulate, distal article reduce to a very small cone (tabication between two distal articles not totally complete). Pereopod 6 and 7 attached to posterior end of pereonites, six-articulate, basis without carina, ischium short and rectangular, merus, carpus and propodus palm carrying row of robust plumose setae, propodus with a proximal projection carrying two grasping spines, dactylus elongate and minutely serrated ventrally. Pereopod 7 slightly more robust than pereopod 6.

Penes ( Fig. 29 ) large, situated laterally, distinctive, oval, length ca 2 times width.

Abdomen ( Fig. 29 ) with a pair of very reduced (almost vestigial) appendages, with two lateral globose lobes provided with bunches of setae and a single dorsal lobe provided with two plumose setae.

Paratype female “a” (4.1 mm) ( Figs. 24 , 27 & 29 ).

Similar to male except for following characteristics: presence of oostegites on pereonites 3 and 4, both setose. Pereonite 2 with short anterolateral projections ventrally. Pereonite 3 and 4 without projections. Flagellum of antenna 1 five-articulate. Gnathopod 2 propodus with a serrated margin between the grasping spine and the Unotch.

Intraspecific variation. The morphological characteristics of mouthparts are similar in the three specimens dissected, with the only difference in that the number of setae in the lobes of maxillae 2 can be 4 or 5. Flagellum of antenna 1 in juveniles (see juvenile AT-1000, Fig. 25 ) is two-articulate and the anterolateral projections of pereonites 2, 3 and 4 are lacking in juvenile specimens and premature females. In the premature female and juvenile the eyes are undistinguishable and the suture between head and pereonite 1 is more marked than in full adult specimens. This complete suture resembles that present in the genera Aeginella Boeck, 1861 , Protellina Stephensen, 1944 , Protellopsis Stebbing, 1888 , Protoaeginella Laubitz & Mills, 1972 or Thorina Stephensen, 1944 among others.

Remarks. The new genus superficially resembles the genus Pedoculina , with similar body shape, having pereopod 3 and 4 provided with one elongate article, pereopod 5 elongate and reduced (4 articles in Pedoculina and 5 in the new genus) and abdomen with lack of clear appendages. The main difference between the two genera is that Selvacaprella gen. nov. has mandibular palp while Pedoculina has no palp. Pereopod 5 is also five-articulate with a minute distal article in the genus Abysicaprella. However both genera clearly differs mainly in: (1) pereopods 3 and 4 are two-articulate in Abysicaprella and uniarticulate in Selvacaprella gen. nov., (2) outer lobe of maxilla 1 has 7 spines in Abysicaprella and apparently 5 in Selvacaprella gen. nov., (3) setal formula is 1-x-y- 1 in Abysicaprella and, apparently, 1-x- 1 in Selvacaprella gen. nov., and (4) Abysicaprella is provided with two large two-articulate abdominal appendages, which are vestigial in the new genus. A weak and elongate pereopod 5 is also present in the genus Aciconula, Propodalirius , Borikenella and some species of Deutella among others, but the new genus can be clearly differentiated from these ones by the combination of the following characters at the same time: pereopod 3 and 4 uni-articulate, pereopod 5 five-articulate, mandible with molar and mandibular palp, and abdominal appendages very reduced. The new genus is also close to the genus Liropus in body shape, antennae, pereopod 3 and 4 uni-articulate and mouthparts. However, in the genus Liropus pereopod 5 is very reduced (with a maximum of 3 articles) and the new genus is provided with a five-articulate pereopod 5.

Figures

FIGURE 24. Selvacaprella jimenoi sp. nov. Lateral and dorsal view of holotype male (MHNUSC 10101) and lateral view of paratype “a” female (MHNUSC 10102).

FIGURE 25. Selvacaprella jimenoi sp. nov. Lateral view of juvenile male and premature female, DIVA-Artabria I 2002, AT- 1000.

FIGURE 26. Selvacaprella jimenoi sp. nov. Mouthparts. Mandibles, maxilla 1 and 2, lower lip and upper lip of holotype male (MHNUSC 10101). Maxilliped figured from juvenile male DIVA-Artabria I 2002, AT-1000.

FIGURE 27. Selvacaprella jimenoi sp. nov. Antenna 1 and 2, gnathopod 1 and 2 of holotype male (MHNUSC 10101), gnathopod 2 of paratype “a” female (MHNUSC 10102).

FIGURE 28. Selvacaprella jimenoi sp. nov. Pereopods 3–7 of holotype male (MHNUSC 10101).

FIGURE 29. Selvacaprella jimenoi sp. nov. Abdomen of holotype male (MHNUSC 10101) and paratype “a” female (MHNUSC 10102).