Medicorophium longisetosum, Myers, Alan A., De-La-Ossa-Carretero, Jose Antonio & Dauvin, Jean-Claude, 2010

Myers, Alan A., De-La-Ossa-Carretero, Jose Antonio & Dauvin, Jean-Claude, 2010, A new species of Medicorophium Bousfield, M. longisetosum n. sp. from the western Mediterranean, coast of Spain, Zootaxa 2450, pp. 53-60 : 54-58

Medicorophium longisetosum n. sp.

( Figs 2–4 )

Type material. HOLOTYPE, Holotype female, 2.5 mm ( MNCNC 20.04/8373). Paratype male, 2.0 mm ( MNCNC 20.04/8374). Four specimens ( MNCNC 20.04/8375), and four specimens in each personal collection of the authors for a total of 17 paratypes same data as holotype.

Type locality. Torreblanca coast (Castellon, East of Spain), 40º11.477´N, 0º15.475´E, depth 13.9 m (Station 5, Table 1 and Figure 1 ).

Etymology. Named after the very long robust setae present on antenna 1.

Description. Based on holotype female, 2.5 mm.

Head. Head with rounded rostrum. Mandible palp article 1 slender, elongate. Antenna 1 peduncular article 1 expanded, broad proximally, posterior margin bearing many very long slender setae; article 2 shorter than article 1, slender, with a few very long slender setae on the posterior margin; article 3 short, less than half length of article 2; flagellum short, about the same length as peduncular article 2. Antenna 2 gland cone very well developed, acute; article 4 very expanded, subovoid, posterior margin with 10–15 long unpaired robust setae, anterior margin with many fine setae; article 5 short, stout, more than half length, but less than half width, of article 4; flagellum shorter than peduncular article 5, composed of 2–3 robust articles.

Pereon. Gnathopod 1 coxa 1 strongly produced, acute; propodus a little over one half length of carpus. Gnathopod 2 dactylus simple, straight. Pereopod 3–4 basis expanded proximally; merus and carpus very short; dactylus extremely long, equal to combined length of merus, carpus and propodus. Pereopod 5 merus elongate; carpus very short. Pereopod 7 propodus almost one and a half times length of carpus.

Pleon. Urosome segments free. Uropod 1 peduncle elongate; rami subequal, half length of peduncle, outer margins with many robust setae. Uropod 2 peduncle without setae; rami subequal, a little shorter than peduncle. Uropod 3 uniramous; peduncle parallel-sided; ramus shorter than peduncle with long terminal setae. Telson subtriangular.

Male paratype, 2.0 mm: similar to that of female. Antenna 2 article 4 posterior margin with fewer (8–10) relatively longer robust setae, article 5 longer relative to article 4.

Habitat. This small species is common along the Valenciana coast and among the 438 specimens collected, 173 were recorded at station 1 Vinaroz ( Table 1 ). Vinaroz ( Table 1 ). Locations where M. longisetosum was found were characterized by fine-sand sediments (0.125mm – 0.25mm) and a mean low percentage of organic matter of 1.89 %.

The associated macrofauna were characterized by high abundances of the bivalve Spisula subtruncata (de la Ossa Carretero et al. 2008) and the tanaid Apseudes latreilli (de la Ossa Carretero et al. 2010). Other abundant species of the order Amphipoda were Autonoe spiniventris , Perioculodes longimanus , Pariambus typicus , Ampelisca typica and Urothoe pulchella .

Distribution. M. longisetosum sp. nov. has been found in fine-sand sediments from the western Mediterranean coast along the Comunidad Valenciana Coast (from 40º28.145´N 0º30.450´E to 38º 46.83' N 0º 12.60' E) with a depth range of 12.4 to 22 m.

Discussion. The genus Medicorophium is, as far as known, endemic to the Mediterranean. Previously five species were known. M. aculeatum ( Chevreux, 1908) ; M. annulatum ( Chevreux, 1908) ; M. minimum ( Schiecke, 1979) ; M. rotundirostre ( Stephensen, 1915) and M. runcicorne ( Della Valle, 1893) . A key to these species is given in Myers, 1982. A key to all the species of Corophiini of Mediterranean Spain, including M. longisetosum sp. nov. is given here. M. longisetosum sp. nov. resembles M. rotundirostre in its rounded rostrum but differs from that species in its expanded article 1 of antenna 1 and in the subovoid article 4 of antenna 2. It differs also in the straight gland cone (curved in M. rotundirostre ), shortened merus of pereopod 3, and slender parallel-sided uropod 3 peduncle. A rounded rostrum is also found in M. annulatum , but in that species it is very short and of different form. As in M. rotundirostre , antenna 2 of M. annulatum has a curved gland cone. M. aculeatum differs from M. longisetosum sp. nov. in its spine-like rostrum, and the male has a well-developed distal spine on article 4 of antenna 2. M.runcicorne has a curved gland cone on antenna 2 (straight in M. longisetosum ) and distinctive recurved robust setae proximally an article 1 of antenna 1. The tiny M. minimum most closely resembles M. longisetosum sp. nov. but that species has a narrow article 1 on antenna 1 which also has a proximal bulge bearing a small recurved robust seta; the gland cone on antenna 2 is weakly curved and pereopods 3–4 have a relatively elongate merus.

Figures

FIGURE 1. Locations where Corophium longisetosum sp. nov. has been found. UTM coordinate system. Grid zone 30 S.

FIGURE 2. Corophium longisetosum sp. nov. Female holotype unless otherwise stated. Torreblanca Coast 40 º 28.145´N 0 º 30.450´E (Castellon, E Spain). Male paratype, same locality.

FIGURE 3. Corophium longisetosum sp. nov. Female holotype. Torreblanca Coast, 40 º 28.145´N 0 º 30.450´E (Castellon, E Spain).

FIGURE 4. Corophium longisetosum sp. nov. Female holotype. Torreblanca Coast, 40 º 28.145´N 0 º 30.450´E (Castellon, E Spain).

Tables

TABLE 1. Locations, geographical coordinates, depth (metres), number of individuals; size (minimum-maximum, mean body size) and physical characteristics of sediment in the stations where Medicorophium longisetosum had been found along the western Mediterranean in Comunidad Valenciana coast, Spain.

Location	Latitude	Longitude	Depth	Nº ind.	Size (mm)	% Mud	% Fine sand	% Medium sand	% Coarsed sand	% Gravel	% Organic matter
1.Vinaroz	40º 28.15' N	0º 30.44' E	15.0	173	1.5–3.1, 2.3	2.2	74.7	11.7	7.2	4.3	2.5
2.Benicarlo	40º 24.55' N	0º 27.70' E	14.0	35	1–4, 2.4	0.7	83.1	5.4	5.0	5.8	1.6
3.Peñiscola	40º 20.79' N	0º 24.99' E	14.8	26	1.1–3, 1.9	1.2	75.6	9.3	5.9	7.9	2.0
4.Alcossebre	40º 14.45' N	0º 18.55' E	12.4	10	1.3–3.1, 2.2	1.5	83.6	5.8	5.2	3.9	1.4
5.Torreblanca	40º 11.83' N	0º 14.59' E	13.9	27	2.1–2.8, 2.5	0.7	77.2	8.4	6.3	7.4	1.6
6.Oropesa	40º 5.586' N	0º 10.62' E	22.0	28	1–3.1, 2.1	6.6	83.0	4.7	4.3	1.3	1.8
7.Canet d'en Berenguer	39º 40.96' N	0º 10.77' W	15.6	1	2.0	1.5	94.9	0.4	1.0	2.1	1.4
8.Puebla de Farnals	39º 31.97' N	0º 15.44' W	18.9	1	1.8	0.3	83.8	9.3	5.6	1.0	1.3
9.Valencia (Vera)	39º 29.12' N	0º 17.45' W	17.2	20	1–3, 2.1	15.8	68.9	4.5	9.3	1.5	2.6
10.Valencia (Pinedo)	39º 24.90' N	0º 17.26' W	20.0	63	1.2–3.1, 2.3	11.0	65.9	4.4	4.9	13.7	2.0
11.Gandia	39º 0.15' N	0º 8.31' W	16.5	36	1.2–3, 2.2	2.8	66.6	9.6	15.6	5.4	2.0
12.Oliva	38º 56.92' N	0º 5.55' W	15.6	17	1.5–3, 2.4	2.3	87.3	4.7	2.9	2.7	2.8
13.Javea	38º 46.83' N	0º 12.60' E	20.0	1	3.0	8.0	81.8	8.1	2.0	0.1	1.6