Hymenodoridae, Lunina & Kulagin & Vereshchaka, 2024

Lunina, Anastasiia, Kulagin, Dmitry & Vereshchaka, Alexander, 2024, The taxonomic status of Hymenodora (Crustacea: Oplophoroidea): morphological and molecular analyses suggest a new family and an undescribed diversity deep in the sea, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 200 (2), pp. 336-351 : 347-348

Family Hymenodoridae fam. nov.

Hymenodoridae LSIDurn:lsid:zoobank.org:act: 1BC06DC5- E4C5-40A9-B593-66BF2F77F6CE

Diagnosis ( Fig. 7A–E ): rostrum dorsally dentate and ventrally unarmed; second maxilla with elongate proximal endite lacking submarginal papilla and lamina; first maxilliped with two-segmented endopod at least two times as long as distal endite; second maxilliped with distal segment suboval ( Hymenodora ) or subtriangular ( Sclerodora ) and attached almost transversely to preceding joint.

Type genus: Hymenodora Sars, 1877 . Genera included: Hymenodora Sars, 1877 , Sclerodora Vereshchaka, Kulagin & Lunina, 2021 .

Remarks: Chace (1986) wrote that mandibles are dissimilar (molar process ‘compressed and sub-bilinear on left’; Chace 1986: 6) in Acanthephyra , Ephyrina , Heterogenys , Hymenodora , Kemphyra , Meningodora and Notostomus , i.e. in Acanthephyridae and Hymenodoridae ; in Janicella , Oplophorus and Systellaspis , mandibles are similar. The shape of the mandibles would be a strong diagnostic character but, after examination of these structures ( Fig. 7A, F, K ), we could not find any objective difference that could definitely be codified. The figures of mandibles in the paper by Chace (1986) also do not show visible variations in the shape of the left molar process. We, therefore, do not include structure of the mandibles in the family diagnoses.

Overall, all three families of Oplophoroidea show a great variability of external characters including the rostrum, carapace, abdomen and pereopods. Diagnostic characters that are invariable within families are, therefore, few and linked only to mouthparts, on which we base the key below.

Figures

Figure 7. Morphological characters distinguishing three families of Oplophoroidea.A–E, Hymenodoridae (Hymenodora frontalis, St. 7497 d271) mandibles (A), second maxilla (B), proximal endite of second maxilla (C), first maxilliped (D) and second maxilliped (E). F–J, Oplophoridae (Systellaspis debilis, 179RT 23.1) mandibles (F), second maxilla (G), proximal endite of second maxilla (H), first maxilliped (I) and second maxilliped (J). K–O, Acanthephyridae (Acanthephyra quadrispinosa Kemp, 1939, AMK87 7277-D13) mandibles (K), second maxilla (L), proximal endite of second maxilla (M), first maxilliped (N) and second maxilliped (O). All scale bars:1 mm.