Liropus willyi, 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 : 161-166

Liropus willyi sp. nov.

( Figs. 7–10 )

Type material. Holotype male, 8.7 mm (used for drawings of lateral view, antennae, gnathopods, pereopods 3–7, abdomen, mouthparts except maxilla 1) (vial with 70% ethanol and 2 slides, mouthparts dissected) ( MHNUSC 10098 ); SELVA 2008 , DRN-30-1, 27 July 2008, 43°48.511’N, 008°51.393’W, 576 m, carbonate crusts.

Paratypes: 1 male (used for drawings of maxilla 1) (dissected, 1 slide) ( MHNUSC 10099 ); DIVA-Artabria II 2008, 27 -EBS, 29 September 2008, 42°45.90’N, 09°41.68’W, 1499 m, muddy bottom ; 1 male not dissected ( MHNUSC 10100 ); DIVA-Artabria II 2008, 07 -DRN-P 0 8, 29 September 2008, 43°24.95’N, 09°25.50’W, 470 m, carbonate crusts .

Diagnosis. Eyes not clearly distinguishable, ommatidia not evident. Two acute anterolateral projections on head. Body dorsally smooth. Anterolateral projections present in pereonites 2, 3 and 4. Flagellum of antenna 1 tenarticulate. Third article of maxilliped palp without distal projection. Mandibular palp with setal formula 0-x-y-1 (from proximal to distal end). Basis of gnathopod 2 as long as pereonite 2. Pereopods 3 and 4 one-articulate. Pereopods 5 three-articulate. Abdomen with two pairs of small appendages and pair of lobes

Etymology. The species is dedicated to Dr. Guillermo Díaz-Agras (“Willy”) from Universidad de Santiago de Compostela for his friendship and support during the cruises where the caprellids of this study were collected. Dr. Díaz-Agras, together with Prof. Dr. Victoriano Urgorri and Dra. Celia Besteiro are in charge of the Marine Biology Research Station of A Graña (Galicia, Spain).

Description. Holotype male (8.7 mm)

Lateral view ( Fig. 7 ). Head with two anterolateral acute projections (see detail in Fig. 7 ). Eyes not clearly distinguishable, ommatidia not evident. Pereonite 1 fused with head, suture present. Pereonite 2 with a pair of acute anterolateral projections. Pereonite 3 and 4 with anterolateral projections; projections provided with an anterior round end laterally and a smaller projection ventrally. Pereonite 5 the longest. Pereonite 7 the shortest.

Gills ( Fig. 7 ). Present at middle of pereonites 3–4, elongate, length about 3 times width.

Mouthparts ( Fig. 8 ). Mandibles with triturative molar, moderately developed and dentate marginally. Threearticulate palp; distal article of palp the longest, with a setal formula 0-x-y-1, being x=3 and y=7; left mandible with incisor and lacinia mobilis five-dentate, followed by three accessory blades; incisor of right mandible fivedentate, lacinia mobilis looking like a blade, followed by an additional blade; molar flake small but apparently present. Upper lip without setae. Lower lip without setae; inner lobes small and globose. Maxilla 1 (figured and described from paratype male) outer lobe carrying six spines, palp two-articulate, distal article with four apical spines and one medial seta. Maxilla 2 inner lobe small, shorter than outer lobe, with five apical setae. Maxilliped inner about 1/3 of outer plate in length, carrying three apical setae and a small tooth; outer plate elongate, with four setae; palp four-articulate, second article the longest, third article without distal projection, fourth article with rows of very fine setulae.

Antennae ( Figs. 7 and 9 ). Antenna 1 ca. 1/4 of body length; flagellum 10-articulate. Antenna 2 clearly shorter than antenna 1; proximal peduncular article with an acute gland cone distally; second peduncular article swollen distally; swimming setae absent; flagellum two-articulate.

Gnathopods ( Figs. 7 and 9 ). Gnathopod 1 basis as long as ischium, merus and carpus combined; grasping margin of propodus with a row of very fine setulae, and several setae; two proximal grasping spines, dactylus bifid distally. Gnathopod 2 inserted on anterior half of pereonite 2; coxa well developed with two projections; basis slightly shorter than pereonite 2, provided with a distal projection; ischium rectangular without projection; merus rounded; carpus short and triangular; propodus oval, palm ventrally crenulated, with proximal projection provided with one grasping spine, and mediodistal small U-notch; dactylus provided with a row of very fine setulae.

Pereopods ( Figs. 7 and 10 ). Pereopod 3 and 4 tiny, one-articulate, with two setae distally. Pereopod 5 threearticulate, inserted on middle of pereonite 5, medial article provided with four setae; distal article very small, provided with a plumose seta. Pereopod 6 and 7 six-articulate, merus, carpus and propodus with a row of ventral setae, propodus with a proximal projection provided with a grasping spine, and a shorter projection with a smaller grasping spine, dactylus elongate with small setulae.

Penes ( Fig. 10 ) large, situated medially, distinctive, oval, length ca 1.5 times width.

Abdomen ( Fig. 10 ) with two pairs of small appendages, each appendage provide with single setae, a pair of lobes, and a single dorsal lobe with two plumose setae.

Intraspecific variation. No females have been found. The other dissected male showed similar mouthparts to the holotype male. Further collections are necessary to describe the characteristics of the female and intraespecific variation.

Remarks (see also remarks under L. vitucoi sp. nov.). Liropus willyi sp. nov. is close to L. vitucoi sp. nov. but can be easily distinguished mainly by the following characteristics: (1) males of L. willyi sp. nov. are clearly larger than those of L. vitucoi sp. nov. (8.7 mm vs 3.9 mm) (2) anterolateral projections on the head are distinctive and acute in L. willyi sp. nov. while small and rounded in L. vitucoi sp. nov., (3) eyes are not clearly distinguishable, with ommatidia not evident in L. willyi sp. nov., while they are well developed in L. vitucoi sp. nov., (4) abdomen is provided with two pair of small appendages in males of L. willyi sp. nov., while there are no appendages in L. vitucoi sp. nov., (5) the proximal grasping spine of propodus of pereopods 6 and 7 is located on a projection in L. willyi sp. nov., while there is no projection in L. vitucoi sp. nov., (6) the shape of anterolateral projections of pereonites 2, 3 and 4 is different between species, (7) third article of the maxilliped palp has no distal projection in L. willyi sp. nov. but this projection is present in L. vitucoi sp. nov., and (8) maxilla 1 outer lobe is provided with 6 spines in L. willyi sp. nov. and 7 in L. vitucoi sp. nov. Although L. willyi sp. nov. superficially resembles L. cachuchoensis , also distributed in deep sea areas of Northern Iberian Peninsula, both species can be easily distinguished by (1) dorsal projections on male pereonites 3, 4 and 5 are absent in L. willyi sp. nov. and present in L. cachuchoensis , (2) anterolateral projections on pereonites 3 and 4 are present in L. willyi sp. nov. and absent in L. cachuchoensis , (3) the setal formula of the mandibular palp is 0-x-y- 1 in L. willyi sp. nov., while in L. cachuchoensis only two apical setae are present, (4) pereopod 5 is three articulate in L. willyi sp. nov. (although the tabication is not totally clear), while it is 2-articulate in L. cachuchoensis , (5) the proximal grasping spine of propodus of pereopods 6 and 7 is located on a projection in L. willyi sp. nov., while there is no projection in L. cachuchoensis , (6) abdominal appendages are present in L. willyi sp. nov., but vestigial in L. cachuchoensis .

Figures

FIGURE 7. Liropus willyi sp. nov. Lateral view of holotype male (MHNUSC 10098) and a detail of the head.

FIGURE 8. Liropus willyi sp. nov. Mouthparts. Maxilliped, upper lip, lower lip, mandibles and maxilla 2 of holotype male (MHNUSC 10098); maxilla 1 of paratype male (MHNUSC 10099).

FIGURE 9. Liropus willyi sp. nov. Antenna 1 and 2, gnathopod 1 and 2 of holotype male (MHNUSC 10098).

FIGURE 10. Liropus willyi sp. nov. Pereopods 3–7 and abdomen of holotype male (MHNUSC 10098).