Haustorioides Oldevig, 1958

Ogawa, Hiroshi, Takada, Yoshitake & Sakuma, Kay, 2021, A New Species of the Sand-burrowing Dogielinotidae, Haustorioides furotai, from Tokyo Bay, Japan (Crustacea: Amphipoda), Species Diversity 26, pp. 65-78 : 67

Genus Haustorioides Oldevig, 1958

[Japanese name: Naminori-sokoebi-zoku]

Haustorioides Oldevig, 1958: 343 ; Barnard 1967: 287; Bousfield and Tzvetkova 1982: 87; Jo 1988: 26–27; Barnard and Karaman 1991: 278; Ren 2006: 447.

Eohaustorioides Bousfield and Tzvetkova, 1982: 92 (type species: Haustorioides japonicus Kamihira, 1977 , fixed by original designation). syn. nov.

Parhaustorioides Ren, 2006: 449–450 , 557 (type species: P. littoralis Ren, 2006 , fixed by original designation). syn. nov.

Type species. Haustorioides munsterhjelmi Oldevig, 1958 , fixed by original designation.

Included species. Haustorioides gurjanovae ; H. indivisus ; H. japonicus ; H. koreanus ; H. latipalpus ; H. littoralis comb. nov.; H. magnus ; and H. nesogenes .

Amended diagnosis. Body smooth. Rostrum distinct. Eyes medium, ovoid or subtriangular. Lateral cephalic lobe subtriangular, lower antennal sinus heavily slanted. Antenna 1 subequal or shorter than antenna 2, without accessory flagellum, peduncles of both antennae shorter than flagellums. Labrum not proboscoid. Mandible: lacking palp, molar strongly triturate, incisor well toothed, lacinia mobilis 4–5 toothed. Labium with small inner lobes. Inner lobe of maxilla 1 short, bearing 2–3 apical plumose setae, outer lobe with long pectinate spines, palp minute, 1-articulated. Palp of maxilliped elongated, 4-articulated, multisetose; outer lobe not elongated.

Coxal plates 1–4 moderately large, deep, without distal process on posterior margins. Coxal plate 1 not reduced, with oblique angle anteroventrally. Gnathopod 2 sexually dimorphic, male gnathopod 2 subchelate, larger than gnathopod 1; female gnathopods 1 and 2 similar, each propodus subtriangular. Pereopods 3–4: each merus and carpus with long setae on posterior margins, each merus with anterodistal lobe; coxal plate 4 excavate posteriorly. Pereopod 5: basis expanded, merus and carpus expanded and with long seta on posterior margin, propodus linear. Pereopod 6: basis and merus expanded, posterior margin of merus with long setae, carpus and propodus linear, anterior margin of dactylus with some setae. Pereopod 7: basis expanded, merus, carpus and propodus linear, anterior margin of dactylus with setae. Coxal gills subrectangular or subtriangular. Oostegites on gnathopod 2 and pereopod 5 subtriangular, oostegites on pereopods 3–4 subrectangular.

Epimeral plates 1–2 each posterodistal corner with or without tooth. Epimeral plate 3 posterodistal corner with small or large tooth. Pleopods very powerful, peduncles short, with some retinacula on medial margins, rami with numerous plumose setae. Urosomites free, urosomite 1 dorsally overhanging 2 and 3. Uropods 1 and 2: biramous, each peduncle with seta on outer margin and without spines on dorsal margin; rami unarmed. Uropod 3 lacking rami. Telson cleft medially or uncleft.

Remarks. Jo (1988) concluded that the genus Eohaustorioides was invalid, but some recent studies (e.g., Barnard and Karaman 1991) without consideration of Jo’s argument, probably because Jo’s paper is not well-known and those recent studies missed his work. In addition, the ML and NJ trees of COI gene strongly suggest that Eohaustorioides is nestled within Haustorioides . Therefore, we highlight Jo (1988) ’s work again and treat Eohaustorioides as an invalid genus.

Additionally, Ren (2006) described the genus Parhaustorioides and suggested that 3 morphological characters were able to distinguish the genus from Haustorioides . However, those characters are also recognized in other Haustorioides species : 1) H. nesogenes with distinct broad lobe on each merus of pereopod 3 and 4 anterodistally, and H. indivisus , H. japonicus , and H. latipalpus with small acute lobes on each merus of pereopod 3 and 4 anterodistally; 2) H. indivisus , H. latipalpus , and H. nesogenes with small tooth on posterodistal corner of epimeral plate 3; and 3) H. indivisus and H. japonicus with uncleft telson. As morphological differences between the two genera are unclear, we consider that Parhaustorioides is a synonym of Haustorioides .