Elena L. Markhaseva

Arctokonstantinus hardingi (Copepoda, Calanoida, Arctokonstantinidae): New family, new genus, and new species from the bathypelagial Arctic Basin

Abstract Arctokonstantinus hardingi is based on a female specimen collected at bathypelagic depths in the Arctic Ocean. The new family has similarities with the family Spinocalanidae (superfamily Spinocalanoidea); however, it does not fit well the diagnosis of the superfamily and family in length of antennule, setation of mandible and maxillule, significantly deviating morphology of maxilla and maxilliped and segmentation of P 1 exopod. Probably the new family represents a new calanoid superfamzly; however, until the male is known the species it is tentatively placed into the superfamily Spinocalanoidea. Arctokonstantinidae is attributed to the Spinocalanoidea based on segmentation and setation pattern of swimming legs P2-P4 and antennule structure. Relying on mouth-part morphology Arctokonstantinus could be considered a predator.

New family and genus Rostrocalanus gen. nov. (Crustacea: Calanoida: Rostrocalanidae fam. nov.) from deep Atlantic waters

Two new species of a new genus and family Rostrocalanidae of benthopelagic clausocalanoid copepods are described from female specimens collected from abyssal depths close to the sea bed in the tropical Atlantic. Rostrocalanus gen. nov. shares the presence of sensory setae on maxilla with other bradfordian families of Clausocalanoidea, but does not fit the diagnosis of any of these families. A family Rostrocalanidae is established for this new genus and is defined by the following derived characters: four‐segmented exopod of mandible supplied with four setae; distal basal endite of maxillule fused to endopod and bearing five setae in total; endopod of maxilla furnished with six worm‐like sensory setae; arrangement of setal numbers on praecoxal endites of maxilliped syncoxa as 0, 1, 2. The establishment of a new clausocalanoidean family sheds new light on the morphological diversity of bradfordian benthopelagic copepods and adds to the biodiversity of the deep‐water calanoid fauna.

Plesioscolecithrix (Copepoda, Calanoida, Scolecitrichidae): A new genus, and a new species from the high Antarctic Weddell Sea (Southern Ocean)

Both sexes of Plesioscolecithrix juhlae gen. et sp. nov. are described from the Weddell Sea shelf, Antarctic, in near-bottom water layers from 167 to 254 m. The new genus has segmentation and setation of the swimming legs P1-P4 typical of the Clausocalanoidea. With the group of clausocalanoidean families Diaixidae Sars, 1902, Parkiidae Ferrari & Markhaseva, 1996 , Phaennidae Sars, 1902, Tharybidae Sars, 1902 and Scolecitrichidae Giesbrecht, 1892 it shares the possession of sensory setae both on the maxilla exopod and on the syncoxa of the maxilliped. The genus is hypothesized to be one of the most primitive among the family Scolecitrichidae and deviations from the usual scolecitrichid morphology are discussed. Its family placement is tentative because of many significant morphological deviations from the scolecitrichid type. The main generic characters distinguishing the new genus from other scolecitrichids are as follows: the number (four) and morphology of thin brush-like sensory setae with very small brushes at the exopod of the maxilla; the simple structure of the male fifth legs (with almost symmetrical coxo- and basipods in both legs); well-developed oral parts in males; the absence of the female fifth legs.

An interim synopsis of the Bradfordian families with a description of Thoxancalanus spinatus (Copepoda: Calanoida), a new diaixid genus and species from the deep Atlantic Ocean

Thoxancalanus spinatus gen. nov., sp. nov. is described from female specimens collected at abyssal depths above the sea bed in the Atlantic Ocean. The new genus belongs among the “Bradfordian” families of the superfamily Clausocalanoidea, characterised by the presence of sensory setae on maxilla and maxilliped and is currently placed in the family Diaixidae of the ancestral group of “Bradfordians” based on setal armament of the maxilliped. Among the Diaixidae the new species is characterised by an oblique row of flat spines on the posterior surfaces of exopod segments 2 in P2–P3, the ornamentation of the basis and exopod of leg 5 with scale-like spinules and by the primitive type of setation of oral parts. Many undescribed benthopelagic “Bradfordian” taxa have been obtained at great depths by the German expeditions DIVA I–III and ANDEEP I–III during the recent decade and studies of their morphology have allowed a critical, interim re-assessment of the composition of “Bradfordian” families. A synopsis of the generic composition of the “Bradfordian” families with diagnoses for the Phaennidae, Scolecitrichidae, Tharybidae, Diaixidae, Parkiidae, Rostrocalanidae and Kyphocalanidae is given with a discussion on the placement of genera within these families. A setation matrix for oral limbs of the currently described “Bradfordian” genera is presented to facilitate their identification. Finally, we give an outlook on promising approaches for elucidating relationships among “Bradfordian” families, both at the family and genera level.

Phaennocalanus unispinosus (Copepoda, Calanoida, Phaennidae): New genus, and new species from the bathypelagial Arctic Basin

Phaennocalanus unispinosus gen. et sp. nov. is based on a female specimen collected at bathypelagic depths in the Arctic Ocean. The new genus is placed in the Phaennidae on account of the number and kind of sensory setae on the maxilla terminal part: the distal basal lobe plus exopod of maxilla bear one worm-like plus seven brush-like sensory setae. There are five setae on the maxilla praecoxal endite and five setae on the praecoxal lobes of syncoxa of the maxilliped. However, it differs from all other phaennid genera in the maxilliped with two setae sclerotized on the distal praecoxal lobe instead of one brush-like seta and one sclerotized seta which is typical of phaennids, and in leg 5 with a single terminal spine and a lack of surface spinulation on this appendage.

New Sensiava species (Copepoda: Calanoida: Diaixidae) from the deep South Atlantic and first description of the female

Females are described for the first time in the genus Sensiava Markhaseva & Schulz, 2006, that was known previously only from males. Four species of this genus are identified from samples collected in the vicinity of the abyssal sea bed. Two species, Sensiava secunda sp. nov. and S. peculiaris sp. nov. are named, and two species are not given names due to a poor condition of the examined specimens and their incomplete descriptions. Sensiava males have also been found in the samples. They share with their male congener Sensiava longiseta Markhaseva & Schulz, 2006 a geniculate right antennule, which is a plesiomorphy observed only in the benthopelagic Clausocalanoidea Giesbrecht, 1893. A differential diagnosis for the genus is given, based on both sexes. Sensiava was previously known only from the Antarctic waters between 63-64ºS, but its distributional range now can be extended significantly further to the north, up to the Equator in the South Atlantic.

New species of Brodskius, Rythabis, and Omorius (Crustacea: Calanoida) from deep Antarctic waters

Three new species of rare benthopelagic clausocalanoidean genera with sensory setae on the maxilla are described from female specimens collected during the German Antarctic expeditions ANDEEP I–III in 2002 and 2005, mainly from abyssal depths close to the sea bed. Brodskius abyssalis sp. nov. differs from congeners by the lack of rostral filaments, two setae on the second segment of antenna exopod, thread‐like tips of maxillary worm‐like sensory setae, and the length of spines of P5 exopod. Rythabis assymmetrica sp. nov. is distinguished from other species in the genus by asymmetrical posterior corners of the prosome, the shape of spermathecae, and setal numbers on the maxillulary distal basal endite plus endopod. Omorius curvispinus sp. nov. is characterized by strongly curved setae of the maxillipedal syncoxa, a comparatively long seta on the basis of antenna, a slightly swollen genital double‐somite, and the shape of spermathecae. The genera Brodskius, Omorius, and Rythabis are recorded for the first time from the southern hemisphere.

Description of Pseudeuchaeta vulgaris n. sp. (Copepoda: Calanoida), a new aetideid species from the deep Pacific Ocean with notes on the biogeography of benthopelagic aetideid calanoids

A new aetideid species Pseudeuchaeta vulgaris sp. nov. is described from females collected at abyssal depths above the seabed from the Clarion Clipperton Fracture Zone in the equatorial northeastern Pacific. It belongs to the benthopelagic group of Pseudeuchaeta Sars, 1905 species. The new species is distinguished from all congeners by two setae present on the maxillule proximal basal endite. It is closely related to P. magna Bradford, 1969 and P. major (Wolfenden, 1911), as all three species share a mandible endopod segment 2 with 4–5 setae and the P1 exopod segment 1 lacking a lateral spine. The new species is the fourth benthopelagic representative of the genus found in the abyssal near-bottom environment of the Pacific Ocean and the first benthopelagic Pseudeuchaeta species recorded in the tropical Pacific. An illustrated overview on the distribution of the genus Pseudeuchaeta is given together with notes on the biogeography of benthopelagic aetideid calanoids in the world’s ocean. While some genera show a nearly worldwide distribution, only few species have been reported in more than one ocean so far. This reflects the undersampling of the benthopelagial in the deep ocean.

A new genus of Arietelloidea (Copepoda, Calanoida), Frankferrarius, from deep waters of the Atlantic Ocean

A new calanoid copepod genus Frankferrarius is based on the female and male of a new species described herein. The specimens were collected in the North and South Atlantic from abyssal depths close to the sea bed during the German expedition DIVA III in 2009. Frankferrarius admirabilis gen. et sp. nov. is a representative of the superfamily Arietelloidea with the praecoxal arthrite of the maxillule heavily sclerotized and a highly specialized, huge maxilla with a well-pronounced articulation between the coxa and basis and with long, grouped endopod setae apparently designed for piercing and grasping prey. This new genus, Frankferrarius, does not completely fit any known family of the Arietelloidea, but is provisionally placed in the Augaptilidae as it shares with this family the general pattern of segmentation and setation of its swimming legs, and a single genital operculum positioned medially on the ventral part of the genital double-somite.

New species of Lucicutia and taxonomic status of L. grandis (Copepoda, Calanoida, Lucicutiidae)

Calanoid copepod specimens attributable to Lucicutia grandis (Giesbrecht, 1895), L. bradyana Cleve, 1904, L. wolfendeni Sewell, 1932, and L. rara Hulsemann, 1966) were studied from antarctic and subantarctic waters collected during RV Eltanin crusies 4–11 and 23, and RV Ob cruises 1 and 3. In addition, identified specimens from the Pacific and Indian Oceans deposited in the systematic collections of the National Museum of Natural History, Smithsonian Institution (Washington, DC, USA) and the Zoological Institute, Russian Academy of Sciences (St Petersburg) were also examined. Both sexes of a new species are described from the eastern tropical Pacific Ocean, L. hulsemannae. Lucicutia hulsemannae is distinguished from L. grandis, L. bradyana and L. wolfendeni by the morphology of the rostrum, genital complex, including plug, and leg 5 of both sexes. Lucicutia bradyana is not found outside the Southern Hemisphere but L. grandis is recorded from the Arabian Sea, the Bay of Bengal, tropical Indian Ocean, as well as its type locality in the eastern tropical Pacific Ocean. Lucicutia wolfendeni is found in all oceans except the Arctic Ocean. The status of L. bradyana, previously rejected as a separate species by Hulsemann (1966), is restored. Lucitutia rara is considered a junior synonym of L. bradyana.