Emertonia berndi Mathiske & Veit-Kohler 2021, sp. nov.

Emertonia berndi Mathiske & Veit-Köhler sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act: 4643898D-D226-48A8-88DA-B5DF414BBFE8

Type material. The examined species will be registered and deposited in the Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Germany. All specimens of the type material were collected in the Southern Ocean, Atlantic Sector. Station numbers indicate “Expedition, station number-deployment number, depth, core-number, sediment horizon”.

Female holotype, SMF 37252 (adult female on 1 slide): RV Polarstern PS 71 — SYSTCO, St. 85-7, 2,964 m, MUC1, 0–1 cm.

Female paratype 1, SMF 37253 (adult female on 1 slide): RV Polarstern PS 71 — SYSTCO, St. 85-5, 2,965 m, MUC3, 0–1 cm.

Female paratype 2, SMF 37254 (adult female on 3 slides): RV Polarstern PS 71 — SYSTCO, St. 13-12, 2,963 m, MUC2, 0–1 cm.

Female paratype 3, SMF 37255 (adult female on 1 slide): RV Polarstern PS 71 — SYSTCO, St. 85-7, 2,964 m, MUC4, 0–1 cm.

Etymology. This species is dedicated to Annabel Mathiske’s father, Dr Bernd Mathiske, for always supporting her and for sparking her interest in marine biology.

Description of female. Habitus (Fig. 24A, B). Total body length measured from anterior tip of rostrum to posterior margin of anal somite (holotype) 0.23 mm, including caudal rami 0.25 mm. Body cylindrical (Fig. 24A, B), slightly depressed dorsoventrally, with prosome slightly wider than urosome. Pores distributed dorsally and laterally on cephalothorax and some on the free somites. Sensilla visible on cephalothorax and somites bearing P2–P5. Second and third prosomites dorsally with short row of microspinules and spinules along entire posterior margin (in third prosomite of minute size). Entire posterior margin of the first three urosomites ornamented with spinules; fourth urosomite ventrolaterally with similar-sized spinules (Fig. 24B) and forming thin, well developed pseudoperculum (Fig. 24A). Anal somite short with minute spinules ventrally and ventrolaterally along posterior margin (Fig. 24A, B).

Caudal rami of adult female (Fig. 24C) cylindrical, approximately three times longer than wide, with five setae: seta I absent; seta II slender, dorsally displaced; seta III short, slender, spine-like, situated dorsolaterally near outer distal corner; seta IV longer, unipinnate, with clearly visible fracture plane and with flexible end; seta V long and slender, bipinnate, with clearly visible fracture plane, situated terminally; seta VI absent; dorsal seta VII slender. Posterior margin of caudal rami ventrally with several spinules (Fig. 24B).

Antennule (Fig. 25). Eight-segmented. Segment I with spinule row along inner margin. Armature formula:

I (0)

II (10) ten slender naked setae of different sizes

III (5) four naked setae, one small spine and one scar (possibly from broken-off seta) along anterior margin

IV (2 + aes) one short naked seta on inner margin and one long naked seta on protrusion accompanying aesthetasc

V (1) one long, naked slender seta

VI (1) one long slender seta with one spinule

VII (3) three naked setae

VIII [6 + (1 + aes)] six slender setae, terminally with one aesthetasc fused at base with one slender naked seta

Antenna (Fig. 26A) Basis unarmed. Endopod two-segmented. Enp1 with one long, naked inner seta. Enp2 subapically with two naked dorsal setae accompanied by a stout spine; apical margin with seven slender naked setae, five of which geniculate. Exopod one-segmented with one naked inner seta, subapically a stout spine and apically a spinule row and two naked setae.

Mandibular palp (Fig. 26B). Palp biramous. Endopod two-segmented; proximal segment with two naked inner setae; distal segment apically with seven naked, slender, basally fused setae of different lengths. Exopod one-third length of endopod, one-segmented, with one dorsally displaced and four apical setae.

Maxillule (Fig. 26C). Praecoxal arthrite apically with four stout and two slender naked setae, two juxtaposed slender setae on anterior surface and one outer spinule. Coxal endite bearing four slender naked setae. Endite of basis armed with four slender naked setae. Enp one-segmented with two slender naked setae. Exp with five slender naked setae.

Maxilla (Fig. 26D). Praecoxa and coxa fused to form a syncoxa bearing three endites. No separation towards basis visible. Proximal endite slightly bilobed, with a slender, naked seta on either lobe. Middle endite with one slender, naked seta. Distal endite armed with two naked setae. Allobasis with stout naked claw-like spine accompanied by three naked setae (one of which with not detectable tip). Enp with four naked setae and one of which slightly displaced.

Maxilliped (Fig. 26E). Syncoxa with a row of spinules accompanying a slender naked seta. Basis asetose. Enp one-segmented with five setae, of which two are slender and naked, two are short slender and naked, and one is stout, long, unipinnate and spine-like.

Swimming legs (Fig. 27; Table 5). With modified rami characteristic for Emertonia species belonging to the andeep -group and naked intercoxal sclerites.

P1 (Fig. 27A). Coxa not visible. Basis with two spinules at inner margin, one inner and one outer pinnate seta. Enp slightly longer than exp, both rami two-segmented and exp2 and enp1 ornamented with spinules on outer margin. Enp1 unarmed, enp2 terminally with one long unipinnate seta and one shorter naked slighty displaced outer seta. Exp1 with one outer naked spine. Exp2 with two outer unipinnate spines and terminally two unipinnate setae.

P2–P4 (Fig. 27B–D). Coxa anteriorly with short row of outward facing flexible setules. Basis of P2–P4 with a spinule row on outer margin. Basis P4 bearing one naked outer seta. Three-segmented exopods slightly longer than endopods with spinules along outer margin and terminally (P2–P4). Exp1 and exp2 with strong serrated outer spines and spinules at the spine’s base. Exp2 P3 with three spinules situated on pronounced ledge on inner margin. Exp2 P4 with one spinule situated on pronounced ledge and one at apical part of inner margin. Exp3 with spine-like spinules at base of all setae (P2–P4). Exp3 P2 and P3 with four elements. Exp3 P2 with two strongly serrated outer spines and two apical setae, the outermost of which long spine-like and serrated at distal half and the innermost long flexible and naked. Exp3 P3 as in P2, but inner apical seta plumose with pinnules on inner side. Exp3 P4 with two serrated spines (one short outer and one long terminal). Endopods P2 and P3 one-segmented with spinules along the outer margin and an additional terminal spinule row. Spinule row on outer margin of enp P2 ending below apical margin in an inward curve. Enp P2 with additionally two very long spinules at two thirds of the outer margin. Enp P3 with three spinules on a ledge on inner margin. Enps P2 and P3 apically with long, rigid, spine-like bipinnate seta. Endopod P4 two-segmented, armed with spinules along outer margin, one inner spinule on enp1 and three slender inner spinules on a ledge on enp2. Enp2 P4 apically with one spine-like seta jaggedly serrated at tip.

P5 (Fig. 28A). Legs of P5 fused in the middle. Exopod and baseoendopod fused, forming a non-segmented plate. Benp with outer long basal naked seta and short spinule rows on surface proximally from exp. Endopodal lobes drawn out with medial cleft, each armed with two pinnate setae. Exopodal parts with three naked setae, with the innermost being shortest and the outer being the longest seta. The outer and inner setae are spine-like while the middle seta is more slender, flexible and outwardly oriented. Exopodal part of right body side with a short spinule row near innermost seta.

P6 and genital field see Fig. 28B. Sixth pair of legs represented by small wavily fused outgrowths bearing two small inner thorns on each side.

Male. Unknown.