Eriopisa mochimae, VAN DER HAM & VONK, 2003

VAN DER HAM, JORIS L. & VONK, RONALD, 2003, A phylogenetic analysis of the Eriopisa complex (Crustacea: Amphipoda: Melitidae) and a new species from beach interstitia in Venezuela, Journal of Natural History 37 (7), pp. 779-796 : 780-789

Eriopisa mochimae n. sp.

Body long and slender. Length of holotype 2.9 mm. Sex not determined. Colourless, blind. Head without lateral lobe. Rostrum absent.

Antenna 1 (figure 2A). Peduncle segments successively shorter, segments 2 and 3 slender. Accessory flagellum (figure 2D) two-segmented, not overreaching top of first flagellum segment. Flagellum with 13 segments.

Antenna 2 (figure 2B). Two-thirds the length of first antenna. Peduncle segments 4 and 5 slender, subequal in length. Flagellum eight-segmented, longer than peduncle segment 5.

Mandible (figure 2E, F). Palp three-segmented; segment 1 with one dorsal seta, segment 2 with two ventral setae and segment 3 with six relatively short mid-ventral setae and three short and two long disto-ventral setae. Palp segment 2 shorter than segment 3. Left and right mandible differ strongly in the form of incisors, spines and molars. Right mandible; incisor with four teeth successively smaller in size, lacinia mobilis with four teeth, spine row with six spines, molar large and rounded, slightly triturative. Edges of molar surface with large number of fine setae. Left mandible; incisor pointed, lacinia mobilis absent, spine row with four short, robust, blunt spines, fifth spine biconcave ending in a surface occupied by fine setae. Left mandibular spine row at right angle to right mandibular spine row. Molar large and rounded, as in right mandibular molar, but with one seta positioned laterally on molar. Edges of molar surface possess short, tooth-like structures.

Maxilla 1 (figure 3D). Inner plate triangular, carrying eight setae. Outer plate with 11 spines. Set of distal spines on left and right palp differ radically. One palp with six short, blunt teeth and two long slender spines. Other palp (figure 3E) more slender, with four spines and no teeth.

Maxilla 2 (figure 3F). Inner lobe with oblique row of eight setae.

Maxilliped (figures 3A–C). Inner lobe with two slender lateral setae and three blunt distal teeth. Outer lobe with five short teeth successively longer in size and three long slender teeth. Palp with four segments. Small ventral lobe at the base of first segment bearing one seta. Anterior side of segment three and anteroventral side of segment four covered with small fine setae. Segment four with two apical ungula.

The lower lip (figure 2C). Large developed mandibular lobes and small visible inner lobes.

Gnathopod 1 (figures 4A, 5A). Coxal plate shorter than wide, with blunt anteroventral corner. Posterior margin of basis with sharp angle. Ventral side of merus covered with small setae. Carpus linear and longer than propodus. Setae on carpus arranged in transverse rows. Propodus small. Palm transverse with several long and short setae.

Gnathopod 2 (figures 4B, 5B). Coxal plate as long as wide. Coxal gill slightly longer than wide and longer than basis, pointed and clearly ribbed. Basis thin and straight. Carpus elongate, triangular, with long transverse row of seven long setae. Ventral side with six groups of one to three setae. Oval propodus elongate, palm covers more than half the propodus length.

Pereiopods 3, 4 (figure 4C, D). Coxal plates slightly wider than long. Fourth coxal plate with a slight posterior excavated margin. Coxal gills twice as long as wide, pointed, longer than basis. Basis linear.

Pereiopod 5 (figure 6B). Coxal plate strongly anteriorly lobed. Coxal gill longer than wide, pointed, but shorter than basis. P5 is much shorter than P6 and P7.

Pereiopod 6 (figure 6A). Coxal plate much shorter than wide. Coxal gill pointed, longer than wide, gill half the length of basis. Basis linear.

Pereiopod 7 (figure 6C). Coxal plate shorter than long. Basis linear. Length subequal to P6.

Epimeral plates 1–3 (figure 1). Posteroventral corner produced into small tooth. First epimeral plate with one posterior setule.

Pleopod 1 (figure 7D). Peduncle without setae, exopod is seven-segmented, endopod is six-segmented.

Pleopod 2. As Pl 1.

Pleopod 3. Peduncle without setae, exopod is eight-segmented, endopod is seven-segmented.

A: P6 and P7 subequal in length (0); P6 shorter than P7 (1) (Stock, 1980).

B: Coxal plate 1 sharply pointed anteriorly (0); coxal plate 1 blunt anteriorly (1) (Stock, 1980).

C: Article 2 of the mandibular palp much shorter than article 3 (0); article 2 of the mandibular palp longer than article 3 (1) (Karaman and Barnard, 1979).

D: Basis P7 expanded (0); basis P7 not expanded (1); basis P7 very expanded (2).

E: Exopodite uropod 3 segment 2 long (0); exopodite uropod 3 segment 2 short (1).

F: Carpus gnathopod 1 linear (0); carpus gnathopod 1 triangular (1).

Uropod 1 (figure 7C). With one strong ventroproximal peduncular spine, two rows of dorsal peduncular spines. Exopod with two dorsomarginal spines and three long and one short distal spine. Exopod is slightly longer than endopod. Endopod without dorsomarginal spines, with two thin distal spines.

Uropod 2 (figure 7B). With several tiny ventrodistal peduncular spines. Exopod with three dorsomarginal spines and three long and two short distal spines. Exopod is slightly longer than endopod. Endopod with no dorsomarginal spines and several thin distal spines.

Uropod 3 (figure 7A). Exopod segment 2 about one-third of the length of segment 1, armed with spines on both lateral and medial margins. Endopod about one-sixth of the length of exopod, carrying one dorsomarginal spine and two distal spines.

Telson (figure 7F). Shorter than peduncle uropod 3 (figure 7E). As long as wide, entirely cleft. Both lobes have two long and two short distal spines.