Miramarassidae

Lowry, J. K., 2006, New families and subfamilies of amphipod crustaceans, Zootaxa 1254, pp. 1-28 : 15-18

Miramarassidae fam. nov.

(Fig. 4)

Type genus

Miramarassa Ortiz, Lalana & Lio, 1999 .

Description

Head. Exposed; deeper than long; lateral cephalic lobe absent; anteroventral margin straight; anteroventral margin not recessed, not excavate; corner subquadrate; rostrum vestigial or absent; eyes poorly developed. Body subcylindrical; without setae; dorsally carinate. Antenna 1 shorter than antenna 2; peduncle with sparse slender setae; peduncular article 1 shorter than article 2; article 2 longer than article 3; article 3 subequal to, or longer than article 1; peduncular articles not geniculate; accessory flagellum short, 1­articulate; primary flagellum 5­ or more articulate; callynophore absent. Antenna 2 peduncle with sparse slender setae or none; without hook­like process. Mouthparts well developed. Mandible incisor dentate; lacinia mobilis present on both sides; accessory setal row without distal tuft; molar dominating mandible; palp 3­articulate. Labium outer lobes smooth. Maxilla 1 inner plate setose along medial margin; outer plate with 11 setalteeth; palp large, 2­articulate. Maxilla 2 inner and outer plates present; inner plate with oblique setal row, with weakly setose medial margin. Maxilliped inner and outer plates well developed; palps well developed; outer plate longer than palp article 1, not longer than palp article 2, apical robust setae absent; palp 4­articulate.

Pereon. Coxae 1–7 well developed. Coxae 1–4 longer than broad or as long as broad, overlapping, coxae not ventrally acute. Coxae 1–3 similar in size, well developed, all subequal in size. Coxae 2–4 none extensively broadened.

Gnathopod 1 smaller (or weaker) than gnathopod 2; similar in form to gnathopod 2; subchelate; coxa subequal to coxa 2; merus and carpus not rotated; carpus/propodus not cantilevered; carpus longer than propodus, not produced along posterior margin of propodus; dactylus large. Gnathopod 2 chelate; coxa smaller than but not hidden by coxa 3; ischium long; merus not fused along, or produced away from, posterior margin of carpus; carpus long, longer than propodus, not produced along posterior margin of propodus; dactylus well developed. Pereopods none prehensile. Pereopods 3–4 not glandular. Pereopod 3 coxa well developed, as long as broad; carpus longer than propodus, not produced; dactylus well developed. Pereopod 4 coxa larger than coxa 3, not ventrally acute, without posteroventral lobe; carpus longer than propodus, not produced; dactylus well developed. Pereopods 5–7 with few robust or slender setae; coxa smaller than coxa 4, with large anteroventral lobe; basis expanded, subrectangular, without posteroventral lobe. Pereopod 6 shorter than, extending beyond propodus of, pereopod 7; basis expanded; dactylus without setae. Pereopod 7 similar in structure to pereopod 6; basis expanded, subovate, without dense slender setae.

Pleon. Pleonites 1–3 without transverse dorsal serrations, 1–2 each with dorsal spine, without lateral teeth or ridging, without dorsal carina; without slender or robust dorsal setae. Epimeron 1 well developed. Urosome not dorsoventrally flattened; urosomites 1–3 free; not carinate; urosomite 1 longer than urosomite 2. Uropods 1–2 apices of rami without robust or embedded setae. Uropods 1–3 similar in structure and size. Uropod 1 peduncle without long plumose setae, without basofacial robust seta (robust or simple), without ventromedial spine. Uropod 2 without dorsal flange, without ventromedial spine; inner ramus shorter than outer ramus. Uropod 3 without medial process; biramous; rami styliform; outer ramus longer than peduncle, without recurved spines; inner ramus subequal to outer ramus, inner ramus not apically setose. Telson laminar; longer than broad; deeply cleft; dorsal or lateral robust setae absent; apical robust setae absent.

Miramarassidae ( Miramarassa sanchezi after Ortiz, Lalana & Lio 1999).

Generic composition

Miramarassa Ortiz, Lalana & Lio, 1999 .

Remarks

There are several distinctive characteristics of the miramarassids: left and right lacinia mobilis present; setae along the entire medial margin of the inner plate of maxilla 1; a well developed oblique setal row on the inner plate of maxilla 2; an elongate ischium of gnathopod 2; absence of a posteroventral lobe on the coxa of pereopod 4; absence of apical robust setae on the rami of uropods 1 and 2; and a deeply cleft telson. Melphidippids have these characteristics, but melphidippids have differently shaped coxae and gnathopods and strongly different uropods.

Iphimediidae are similar to miramarassids in the characters above except for the well developed oblique setal row on the inner plate of maxilla 2 which is usually absent in iphimediids although a few facial setae are sometimes present. The second gnathopods are very distinctive and similar between these two groups. Iphimediids differ from miramarassids in having styliform mouthparts, a small molar, only a left lacinia mobilis, acuminate coxae and never with a deeply cleft telson. Based on the similarities between these taxa it is possible to think of miramarassids as a primitive sister taxon to the iphimediids –the way an iphimediid may have looked before it developed a highly modified mouthpart bundle and acuminate coxae.

There are certain characteristics which remain unknown, such as the possibility of a callynophore in the adult male, the relative lengths of antennae 1 and 2 and the surface of the molar which appears to be non­triturative, but is not described.

The relationship of this taxon within the amphipods remains uncertain.

Distribution

Cuba.