. PROC. BIOL. SOC. WASH. 104(2), 1991, pp. 253-268 REVISION OF IPHIMEDIIDAE AND SIMILAR FAMILIES (AMPHIPODA: GAMMARIDEA) C. O. Coleman and J. L. Barnard Abstract.— The amphipod families Acanthonotozomatidae, Amathillopsi- dae, Astryidae, Epimeriidae (=Paramphithoidae), Iphimediidae, Ochlesidae and Stilipedidae are rediagnosed and three new families, Acanthonotozomel- lidae, Dikwidae, and Odiidae are described. New keys distinguish these fam- ilies; other similar families, Lafystiidae and Laphystiopsidae are diagnosed and included in the keys. In the process of rediagnosing the Och- more discretely from Iphimediidae, without lesidae Stebbing, 1910 (see Coleman & resorting to the difficult judgment about the Barnard 1991a), as a family distinct from conical or quadrate shapes of the mouthpart Iphimediidae, we determined that other al- group. Within the Iphimediidae two prin- terations to the taxonomy of the Iphime- cipal groups remain: those genera similar to diidae and Epimeriidae were necessary. Our Iphimedia and those genera similar to Acan- contribution here offers a different division thonotozoma. These two groups are distin- than used in the past based on characters guished and the Acanthonotozomatidae are not previously used or inconsistently used revived. The new family Acanthonotozo- to define these groups. For example, we mellidae are split away from Acanthono- found relatively good consistency of char- tozomatidae. acters on incisors, rakers, gnathopods and coxae in proposing this new division of the Methods taxa. All diagnoses presented herein follow the Discussion format of comparison to the model amphi- pod known as the "basic gammaridean" By using characters other than reduction pubUshed by Barnard (1969:50, figs. 1, 2). of maxillipedal palp, we are able to tighten The formula for setae on the mandibular the diagnosis of Ochlesidae, but this re- palp was invented by Stock (1974). Two quires, at the same time, the removal of the keys with different starting points are pre- genera Odius and Postodius from the Iphi- sented. To account for possible differing in- mediidae to form the contents ofa new fam- terpretations of certain characters some taxa ily Odiidae, the removal of the peculiar Di- are entered twice in the keys. For example, kwa from its paramphithoid-iphimediid Dikwidae are entered twice to treat the al- associations to form a unique family Dikwi- ternatives of coxa 1 acuminate and tapering, dae, and the reinstatement of the Amathil- or subtruncate and not tapering. lopsidae (an old family synonymized with Epimeriidae some years ago). The genera Key I to the Families of the Parepimeria Chevreux (1911) and Parepi- Iphimediidae and Similar Taxa meriella Schellenberg (1931) are removed to the Pleustidae. By removing the above 1 Mandibular rakers present 2 contents from the two families, the diag- - Mandibular rakers absent 10 nosis of Epimeriidae becomes strengthened 2. Coxa 1 truncate, not pointed or ta- and these amphipods can be distinguished pering 3 . 254 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON - Coxa 1 tapering or pointed 7 - Carpus of gnathopod 2 not pro- 3. Gnathopod 1 propodochelate, duced, molar absent head deformed Dikwidae Acanthonotozomatidae - Gnathopod 1 not propodochelate 4 Key 2 to the Families of the Iphimediidae and Similar Taxa 4. Molar triturative .. Amathillopsidae - Molar not triturative, or absent . 5 1. Gnathopod 1 propodochelate .... 2 5. Neither molar present nor incisor - Gnathopod 1 subchelate or simple broadened . Acanthonotozomellidae 4 - Either molar present or incisor 2. Gnathopod 2 enlarged, subchelate, broadened 6 carpus lobate, (molar triturative, 6. Small setose molar present, inci- rakers present) Odiidae sors narrow Astryidae - Gnathopod 2 feeble, propodoche- - Molar absent, incisors very broad late or simple, carpus not lobate 3 certain Stilipedidae 3. Rakers present, gnathopod 2 sim- 7. Gnathopod 2 much broader than ple Dikwidae gnathopod 1 , carpus lobate . Odiidae - Rakers absent, gnathopod 2 pro- - Gnathopod 2 almost as slender as podochelate Iphimediidae gnathopod 1 , carpus not lobate 8 4. Carpus of gnathopod 2 produced 8. Gnathopod 1 propodochelate, Ochlesidae head deformed and reduced .... - Carpus of gnathopod 2 not pro- Dikwidae duced 5 - Gnathopod 1 simple, head formed 5. Coxa 1 tapering or pointed 6 normally 9 - Coxa 1 not tapering or pointed . 8 9. Molar absent 6. Molar produced, triturative or se- Acanthonotozomellidae tose Epimeriidae - Molar present Epimeriidae - Molar reduced or absent, not tritu- 10. Coxa 1 truncate below 11 rative or setose 7 - Coxa 1 tapering below 14 7. Rakers absent 11. Gnathopods 1-2 propodochelate Acanthonotozomatidae Iphimediidae - Rakers present - Gnathopods 1-2 not propodoche- Acanthonotozomellidae late 12 8. Incisors extremely broad and flat 12. Body and incisors ofmandible very Stilipedidae broad and flat Stilipedidae - Incisors of ordinary width and not - Body and incisors of mandible or- extremely flat 9 dinary 13 9. Rakers present 10 13. Gnathopod 2 subchelate, molar - Rakers absent 11 absent, coxa 4 not reduced, point- 1 0. Molar only setose, gnathopods fee- ed Lafystiidae ble, propodus smaller than carpus, - Gnathopod 2 simple, molar pres- rectangular or ovate Astryidae ent, all coxae 1-4 reduced, trun- - Molar triturative, gnathopods en- cate Laphystiopsidae larged, propodus larger than car- 14. Gnathopod 2 propodochelate . pus, almost almond-shaped Iphimediidae Amathillopsidae - Gnathopod 2 not propodochelate - Molar absent, gnathopods feeble, 15 propodus dominated by carpus, 15. Carpus of gnathopod 2 produced, subrectangular molar present Ochlesidae Acanthonotozomellidae VOLUME 104, NUMBER 2 255 1 1 . Gnathopod 2 subchelate, molar least slightly shorter than 4. Gnathopods of absent, coxa 4 not reduced, taper- moderate size and with short articles 5-6, ing Lafystiidae not flagellar, gnathopod 2 usually slightly - Gnathopod 2 simple, molar pres- longer than gnathopod 1; gnathopods 1-2 ent, all coxae 1-4 reduced, trun- propodosubchelate, carpi lobed, propodi cate Laphystiopsidae enlarged and almost almond-shaped. Arti- cle 2 of pereopods 5-7 occasionally with Special Couplets Distinguishing posterior cusps or teeth. Epimeron 3 lacking Ochlesidae and Odiidae 2 large cusps. Urosomites free. Uropods 1- 3 biramous. Rami of uropod 3 flattened, A. Pereonites 1-6 flat and keel-like lanceolate, 1 -articulate. Telson entire or dorsally, flagella of both antennae weakly incised, generally not longer than 1-2 reduced, merus and carpus of peduncle of uropod 3. gnathopod 2 produced, palp of Relationship.— T>\^Qnng from the Epi- maxilla 1 reduced, inner plate of meriidae in the weaker rostrum, slightly maxilla 1 reduced B shortened and unpointed coxa 1 , lobate car- B. Gnathopod 1 simple, gnathopod 2 pi and enlarged almond-shaped propodi of simple, coxae 1 and 4 shorter than gnathopods, and presence of large inner coxae 2-3 Ochlesidae lobes on the lower lip. - 1 propodochelate, Gnathopod List of genera.— Amathillopsis Heller, coxae 1 gnathopod 2 subchelate, and 1875 (=Acanthopleustes Holmes, 1908). 4 ordinary Odiidae Epimeriidae Amathillopsidae Epimerinae [sic] Boeck, 1871:183. Amathillopsidae Pirlot, 1934:201. Paramphithoidae Stebbing, 1906:320. Diagnosis.— Body compressed. Rostrum Diagnosis. —Body compressed, with dor- of medium size or very small (not "well sal teeth sometimes confined to metasome, developed"). Antennae elongate, flagella or urosome, and sometimes weak (Epimeri- with 5+ articles; accessory flagellum 1-2 ella). Rostrum well developed. Antennae articulate. Mouthpart part field quadrately elongate, flagella with 5 + articles; accessory developed (box-like). Epistome and labrum flagellum 0-1 articulate. Mouthpart part broad, short, entire. Incisor of mandible or- field quadrately developed (box-like). Ep- dinary, toothed; raker row strong; molar istome and labrum broad, short, incised or large and triturative, palp always present, entire. Incisor of mandible ordinary, 3-articulate. Lower lip with large fleshy in- toothed; raker row strong; molar large and ner lobes, without distinct inner notches. triturative or reduced, conical and pubes- Inner plate of maxilla 1 ordinary, apically cent {Epimeriella and Epimeria victoria and somewhat medially setose; outer plate Hurley, 1957); palp always present, 3-artic- oblique, normally spinose; palp large, 2-ar- ulate. Lower lip without inner lobes, with- ticulate. Inner plate of maxilla 2 without out distinct inner notches. Inner plate of facial setae. Palp of maxilliped 4-articulate, maxilla 1 ordinary, medially setose (except article 2 not produced medially. Coxae 2- Uschakoviella); outer plate oblique, nor- 3 more or less acuminate, ventral margins mally spinose; palp large, 2-articulate. Inner fitting normal ventral parabolic curve of an- plate of maxilla 2 without facial setae. Palp terior coxae; coxa 1 but not 4 shortened, of maxilliped 3-4-articulate, article 2 not coxa 1 scarcely to not acuminate, mostly produced medially. Coxae \-^ acuminate, truncate, coxa 4 not strictly acuminate, with ventral margins fitting normal ventral par- weak or no posteroventral lobe, coxa 5 at abolic curve of anterior coxae; coxae 1 and ; 256 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 4 not shortened, coxa 4 with large postero- gellum. Most Pardaliscidae have evenly ex- ventral lobe, coxa 5 at least slightly shorter tending coxae 1-7, there being little differ- than 4. Gnathopods feeble and with elon- ence in the ventral extension of these plates. gate articles