Photis inornatus, Myers, Alan A., Rigolet, Carine, Thiébaut, Eric & Dubois, Stanislas F., 2012

Myers, Alan A., Rigolet, Carine, Thiébaut, Eric & Dubois, Stanislas F., 2012, A new species of amphipod, Photis inornatus sp. nov. (Corophiidea, Photidae) from a ‘ Haploops community’ in Brittany, Zootaxa 3236, pp. 55-61 : 56-60

Photis inornatus sp. nov.

( Figs 1–3 )

Type material. HOLOTYPE, Holotype female, 3.2 mm (MNHN-IU-2009-585), Paratypes: 4 males, 12 females, same data as holotype (MNHN-IU-2009-586).

Type locality. Bay of Concarneau (47°44'16.3"N; 3°53'34.7"W and 47°48'32.1"N; 3°55'31.8"W)

Etymology. Latin inornata, meaning unornamented, referring to the uniform palms of the gnathopods in both sexes.

Description. Based on Paratype male MNHN-IU-2009-586, 3.4 mm.

Head. Head with strongly forward produced, rounded eye lobe. Eye, black, composed of many ommatidea, situated fully in eye lobe. Antenna 1 almost equal to body length; peduncular article 3 longer than 2; flagellum longer than peduncle, composed of about 13 flagellar articles. Antenna 2 longer than 1; peduncular articles 4 and 5 subequal in length; flagellum longer than peduncle, with about 20 articles. Labrum anterior margin weakly setiferous. Mandible with strong molar, palp 3-articulate, article 1 very short, article 2 much longer than 3, article 3 subsymmetrical, spatulate, with long distal setae. Maxilla 1 inner plate small, subtriangular, asetiferous, palp 2- articulate, article 2 extending well beyond outer plate. Maxilla 2 inner plate with oblique setal row. Labium mandibular processes rounded. Maxilliped outer plate posterior margin scalloped, palp very long, article 2 elongate, extending well beyond distal margin of outer plate.

Pereon. Gnathopod 1 coxa unproduced, rounded; basis moderately stout, about two and a half times as long as broad, with 6–8 long setae on the posterior margin; carpus and propodus subequal; propodus palm evenly rounded delineated by stout robust seta, but evenly continuous with posterior margin; dactylus strong, overlapping position of robust seta. Gnathopod 2 similar to gnathopod 1, basis stout, length less than twice breadth; carpus a little shorter than propodus; propodus subovoid, palm scarcely delineated, delimited by robust seta; dactylus strong, overlapping position of robust seta. Pereopods 3–4 stout, coxa deeper than broad: basis strongly setiferous; dactylus elongate, shorter than propodus. Pereopod 5 basis broad, less than one and one half times as long as broad, posterior margin with long setae; propodus palm with long robust seta; dactylus short, recurved with accessory spine on anterior margin. Pereopod 6 dactylus with small accessory spine on anterior margin. Pereopod 7 basis anterior margin sinuous; dactylus lacking accessory spine.

Pleon. Epimera 1–3 rounded. Uropod 1 elongate, peduncle much longer than rami; inner ramus a little longer than outer, outer margin with few robust setae; outer ramus, outer margin with numerous robust setae. Uropod 2 peduncle a little longer than rami, rami subequal with robust setae. Uropod 3 peduncle subequal in length with outer ramus; inner ramus scarcely one third length of outer ramus, with small second article and lacking setae, outer ramus slender, with small second article bearing two long distal setae. Telson dorsoventrally thickened, distal margin weakly convex, with a single fine seta on either side.

Female. Based on Holotype female MNHN-IU-2009-585, 3.2 mm, Scarcely differing from male. Gnathopod 2 basis a little less stout.

Habitat. Individuals were found between 20 and 35 m depth in muddy sediments (mud percent ranging from 56% to 82%) within the Haploops community. This species was absent from surrounding sampled benthic communities, i.e. Owenia fusiformis fine sand community (% mud = 17–19%; depth ~ 30 m), Amphiura filiformis muddy sand community (% mud = 46–55%; depth ~ 25 m), and Sternaspis scutata muddy community (% mud = 58–60%; depth ~ 20 m).

Distribution. Currently known only from the type locality.

Discussion. Photis inornatus sp.nov. is unique amongst world Photis species in having unornamented palms on gnathopods 1–2 in both sexes. It also differs from other North Atlantic species in having antennae equal in length to the body

Photis inornatus was found to be restricted to the Haploops muddy habitat, while other similar sedimentary environments were prospected (Table 1). Within this former habitat, it was present in most sampled stations at densities ranging between 0 and 125 ind.m -2. Over the year, it was only absent during winter samples (February 2010). Conversely, P. longicaudata was reported in all habitats investigated in the bay of Concarneau, indicated that both species may live in sympatry. It is also hypothesized here a close relationship between Haploops nirae and P. i n o rnatus, either directly due to inter-specific relationships or indirectly due to the special features created by Haploops tube mats.

A key to the European Atlantic species of Photis is provided below.

TABLE 1. Mean and min-max densities (ind.m -2) and occurrence frequency of Photis inornatus sp. nov. and Photis longicau-

data in the Bay of Concarneau, France, in 2009–2010.

Mean density (± SD) (ind.m -2) Frequency of occurrence min-maxvalues

0–100 0–124

Figures

FIGURE 1. Photis inornatus sp. nov., male paratype, 3.4 mm. Bay of Concarneau

FIGURE 2. Photis inornatus sp. nov., male paratype, 3.5 mm, female holotype 3.3 mm. Bay of Concarneau

FIGURE 3. Photis inornatus sp. nov., male paratype, 3.5 mm, Bay of Concarneau.