MEGALANCEOLIDAE, Zeidler, 2009

Zeidler, Wolfgang, 2009, A review of the hyperiidean amphipod superfamily Lanceoloidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 2000, pp. 1-117 : 74-75

Family MEGALANCEOLIDAE , new family

Diagnosis. Body length of mature specimens 40–95 mm. Pereon broadened dorsoventrally or relatively slender. Head with short rostrum. Eyes relatively large, round or kidney shaped, reniform. Pereonites all separate. Coxae separate from pereonites. Antennae 1 with stout callynophore, peduncle 3-articulate. Antennae 2 much longer than A1. Mandibles with relatively massive palp, longer than body; third article of palp shorter than second or marginally longer than first and second combined; left with lacinia mobilis almost as wide as incisor. Maxillae 1 with broad, oval or rectangular palp; outer lobe relatively narrow, distal margin armed with five stout setae; inner lobe, narrow, rounded, barely reaching base of palp. Maxillae 2 with relatively narrow lobes. Maxilliped with oval outer lobes; inner lobes relatively broad or slender, about as long as half-length outer lobes or longer, mostly separate. Gnathopod 1 simple with carpus marginally broadened distally with relatively straight distal margin. Gnathopod 2 simple, slightly longer and more slender than G1. Pereopods 3 & 4 simple, with or without small, rectractile dactylus. Pereopods 5–7 with retractile dactylus, more or less hooded. Urosomite 2–3 with partial suture ventrally. Uropoda relatively broad or slender, with articulated exopoda and endopoda. Telson elongate with rounded or pointed apex, reaching, or just exceeding, limit of peduncle of U3. Gills on pereonites 2–6. Oostegites on pereonites 2–5.

Two genera: Megalanceola and Megalanceoloides gen. nov.

Remarks. This new family is proposed here to accommodate the type genus Megalanceola (and Megalanceoloides gen. nov.) which, prior to this study, was placed in the family Lanceolidae . Megalanceola currently consists of two species, M. stephenseni ( Chevreux, 1920) and M. remipes ( Barnard, 1932) . Megalanceola stephenseni resembles Lanceola in having pereopods 5–7 with rectractile and hooded dactyls, but differs primarily in the morphology of the mouthparts. In particular the mandibles have a relatively massive palp and the incisor, although broad, is relatively narrower than for other lanceolids because the distal half of the mandibular body, above the insertion of the palp, is considerably more narrowed. Also, the left mandibles have a well developed lacinia mobilis that is about as wide as the incisor and the first maxillae have relatively narrow outer lobes and relatively smaller and shorter inner lobes that barely reach the base of the palp. These characters are unlike any other lanceolid, making it difficult to accept a close phylogenetic affinity with Lanceola or Scypholanceola .

Megalanceola remipes is similar to M. stephenseni in the morphology of the mouthparts, head, antennae and the relative position of the eyes but possess a number of characters that set it apart. It differs primarily in that the pereon is not dorso-ventrally broadened, the body (head, pereon, coxae & pleon) is highly sculptured, the third article of the mandibular palp is subequal in length to the first two articles combined, the inner lobes of the maxilliped are almost as long as the outer ones, pereopods 3 & 4 also have retractile dactyls, pereopods 3–5 have extremely broad articles and pereopods 3–7 do not have a spoon-shaped process for the retractile dactyls typical of other lanceolids. Thus, a new genus, Megalanceoloides gen. nov., is proposed for this species. The unique characters of this species further demonstrate that it, together with M. stephenseni , does not belong with the Lanceolidae . However, based on the morphology of the mouthparts, head and antennae, the two appear to be related and are thus placed together in the new family Megalanceolidae .