Liropus isabelensis, Sánchez-Moyano & García-Asencio & Guerra-García, 2014

Liropus isabelensis View in CoL sp. nov.

( Figures 15–18 View Figure 15 View Figure 16 View Figure 17 View Figure 18 )

Type material

Holotype male plus 1 slide ( MNCN 20.04 About MNCN /9226) , Allotype female plus 1 slide ( MNCN 20.04 About MNCN /9227) . Paratypes: 2 males ( MNCN 20.04 About MNCN /9228-29) , 1 female ( MNCN 20.04 About MNCN /9230) .

Additional material examined

St1: 1 male; St6: 3 males, 3 females; St8: 3 males, 1 female, 1 juvenile.

Type locality

Cerro Pelón (Isla Isabel), México, 25 m, on hydroids and bryozoans.

Etymology

Named isabelensis alluding to the National Park of Isla Isabel ( Nayarit), México.

Diagnosis

Eyes present. Body dorsally smooth. Anterolateral acute and downward-directed projections on pereonite 2 and mediolateral on pereonite 3 in males and absent in females. Flagellum of antenna 1 five-articulate. Gnathopod 2 basis slightly longer than pereonite 2; ischium and propodus elongated. Pereopods 3, 4 and 5 one-articulate. Abdomen without appendages in males.

Description

Male holotype. Body length: 3.25 mm.

Lateral and dorsal view ( Figure 15 View Figure 15 ): Body dorsally smooth. Head rounded, eyes present. Pereonite 1 fused with head, suture present. Pereonite 2 with a pair of anterolateral acute and directed downwards projections. Pereonite 3 with a pair of mediolateral projections. Pereonite 5 the longest. Pereonite 7 the shortest.

Gills ( Figure 15 View Figure 15 ): Present on pereonites 3–4, oval. Gills on pereonite 3 about 2.5 times longer than those on pereonite 4.

Mouthparts ( Figure 16 View Figure 16 ): Upper lip symmetrically bilobed with small setulae apically. Mandibles with molar process and three-articulate palp; distal article of palp the longest, with one seta apically (lost in the dissection); second article of palp with one distal plumose seta; incisor and lacinia mobilis five-toothed; left and right mandibles with three and two pectinated setae respectively. Lower lip with inner lobes well-demarcated, inner and outer lobes setose apically. Maxilla 1 outer lobe carrying five robust setae; distal article of the palp with five apical setae. Maxilla 2 inner lobe oval, carrying five distal setae, and outer lobe rectangular, with six apical setae. Maxilliped inner plate rectangular carrying from inner to outer margin a nodular seta, two plumose setae and one seta; outer plate with four setae and one plumose seta apically; palp four-articulate, scarcely setose, third article provided with a projection.

Antennae ( Figures 15 View Figure 15 and 17 View Figure 17 ): Antenna 1 about one-third of body length; peduncle scarcely setose; flagellum five-articulate. Antenna 2 about two-thirds of antenna 1; proximal peduncular article with a developed acute projection distally; swimming setae absent; flagellum two-articulate.

Gnathopods ( Figure 17 View Figure 17 ): Gnathopod 1 basis longer than ischium, merus and carpus combined (length about 1.5 times); propodus palm with proximal grasping spine and setae along the palm present. Gnathopod 2 inserted on the anterior half of pereonite 2; basis slightly longer than pereonite 2, with tiny tubercles on the proximal half; ischium elongated, half as long as basis; merus rounded; carpus short and triangular; propodus elongated, longer than basis, and four times as long as wide; palm with proximal projection with one grasping spine, followed by another proximal acute projection, margin setose; dactylus with setulae and widened medially.

Pereopods ( Figure 18 View Figure 18 ): Pereopod 3 and 4 small, one-articulate, with three or four setae apically, respectively. Pereopod 5 one-articulate, with five setae and one plumose seta apically. Pereopod 6–7 increasing in length, six-articulate and attached to the posterior end of the pereonite; propodus palm carrying a row of robust setae.

Penes ( Figure 18 View Figure 18 ): Situated medially, rounded.

Abdomen ( Figure 18 View Figure 18 ): A pair of lateral lobes, and a single dorsal lobe.

Allotype female. Body length: 2.6 mm. Similar to male except for the following characteristics ( Figures 15 View Figure 15 and 17 View Figure 17 ): oostegites present, being slightly setose on pereonite 3 and 4; pereonite 2 and 3 lacking anterolateral and lateral projections, respectively; gnathopod 2 ischium less elongated than in male (one-quarter as long as basis), propodus oval, as long as basis, with only one proximal projection, dactylus not setose. Abdomen with a pair of lateral lobes and single dorsal lobe ( Figure 18 View Figure 18 ).

Remarks

Liropus isabelensis represents the 10th species from the genus Liropus Mayer, 1890 . The other species included in the genus are as follows: L. africanus Mayer, 1920 , L. azorensis Guerra-García, 2004 , L. cachuchoensis Guerra-García, 2008 , L. elongatus Mayer, 1890 , L. gracilis Chevreux, 1927 , L. japonicus Mori, 1995 , L. minimus Mayer, 1890 , L. minusculus Guerra-García and Hendrycks, 2013 and L. nelsonae Guerra-García, 2003 . Most of the species have an Atlantic or Mediterranean distribution except L. japonicus , from Japanese waters, and L. minusculus , from California, USA. Therefore, the new species is the second record of the genus Liropus from the East Pacific coast.

A morphological comparison among Liropus species is given in Table 3. Liropus isabelensis can be distinguished from all other species mainly by the following characteristics: anterolateral acute and downwards-directed projections on pereonite 2, presence of mediolateral projections on pereonites 3 and gnathopod 2 ischium elongated. Liropus minusculus is the geographically nearer species and shares some characteristics with L. isabelensis such as pereopod 5 one-articulate and the anterolateral projections in pereonite 2 although this is more acute and downwards directed in the latter. Both species have the smallest size, although L. africanus and L. japonicus are also characterized by a very small size.

Habitat

This species was found attached to species of Thecata and Athecata hydroids, gorgonian ( Muricea cf. californica ), a bryozoan ( Bugula sp.), the seaweed Zonaria cf. farlowii with epiphytic hydroids and several red seaweeds. They occur from 3 to 25 m deep, although always in low densities. Other caprellids, such as Paracaprella spp. and Aciconula acanthosoma , live on these substrates together with L. isabelensis .

Distribution

Liropus isabelensis has been found from the type locality, Isla Isabel , México ( St 6, Bahía Tiburón ; St 8, Cerro Pelón ), and Mazatlán ( St 1, Isla de los Pájaros) .