Eudorellopsis dentata, Mühlenhardt-Siegel, 2025

Eudorellopsis dentata n.sp.

( Figures 9–12 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12 )

Material:

Holotype: ovigerous female ( ZMH K 64947 View Materials ) ( 15 July 2009), SW Atlantic, Argentine Basin, FS “Meteor”cruise Me 79/1, station: #533, 36° 00.20'S 49° 01.96'W, 4602 m depth; gear: EBS. GoogleMaps

Paratypes:

Argentine Basin:

#532—EBS: 1 manca, 1 ovigerous female; 1 juvenile male (pleopods not yet developed) ( ZMH K 64975 View Materials ), 1 ovigerous female ( 5.3 mm long, dissected, ZMH K 64948 View Materials ) ,

# 533—EBS: 11 mancae, 7 preparatory females (1 broken after pereionite 4, 1 broken after pleonite 2), 3 ovigerous females, 1 subadult male (developing pleopods) ( ZMH K 64976 View Materials ); 1 adult male (figured, ZMH K 64949 View Materials ) ;

# 534—EBS: 9 mancae, 6 preparatory females (1 figured), 2 ovigerous females, 2 adult males (one of them broken after carapace), 2 adult males (1 dryed) ( ZMH K 64977 View Materials ) .

Etymology.—The new species is named “dentata ” because of the dentate dorsomediane and lateral ridges and the anterior margin of the carapace.

Diagnosis.—Dorsomedian line of carapace with 9 teeth, the anteriormost largest; laterally a serrate ridge running from anterior part to at least hind quarter of the carapace; some females can carry not only one but 2 weak lateral folds with teeth; uropod endopod sub equal in length to exopod.

Description.—Based on holotype ( Fig. 9 View FIGURE 9 ), ovigerous female, 5.1 mm long ZMH: K 64947 View Materials

Carapace as long as free thoracic segments, dorsomedian line with 9 teeth, the first biggest, followed by 1 or 2 (in paratype ZMH K 64948 View Materials ) in a single row and 3 pairs of dorsomedian teeth; laterally a serrate ridge running from anterior margin to at least hind quarter; pseudorostral lobes directed upwards; siphonal tube short, not protruding; ocular lobe rudimentary; eye lenses missing. Antennal notch in anterior ventral corner; anterolateral tooth not developed; anterior and ventral margin of carapace strongly serrate; integument with scaly structure.

Five free thoracic segments visible, dorsal teeth at pereionite segments 1–4.

Pleon 1.1 times longer than carapace plus free thoracic segments.

Pleotelson 1.3 times longer than wide, little protruding between uropods, anal valves visible in dorsal view.

Appendages: ovigerous female, 5.3 mm long ( paratype ZMH: K 64948 View Materials )

Antenna 1 ( Fig. 10 View FIGURE 10 , A 1 View FIGURE 1 ): relative length of peduncle articles 1 to 3: 59/24/17; geniculated between peduncle articles 1 and 2; basal article with 3 plumose setae, second article with 3 plumose and 2 simple setae, third article with one slender simple seta, 2 slender plumose setae on inner distal edge, 5 plumose setae along outer distal margin; accessory flagellum longer than basal article of main flagellum, with 3 long simple setae; main flagellum 3-articulated, basal article with 3 long simple setae, second article with 2 simple setae, third article with 3 simple setae.

Maxilliped 2 ( Fig. 10 View FIGURE 10 , Mxp2): B/R ratio 0.5, relative length of articles I to D: 8/29/29/22/13;

basis with one strong plumose seta; ischium and merus unarmed; carpus with 11 plumose setae; propodus with one strong plumose seta on outer margin and 8 simple setae on inner margin; dactylus with 1 stronger terminal seta and 6 sub terminal simple setae; 5 strong setae on rudimentary oostegite.

Maxilliped 3 ( Fig. 10 View FIGURE 10 , Mxp3): B/R ratio 1.1, relative length of articles I to D: 13/20/32/18/17;

basis with 3 plumose setae on inner margin and 4 plumose setae on outer distal corner; ischium with 3 simple setae; merus with one plumose seta and 2 simple setae; carpus one simple seta and 2 plumose setae;

propodus with 1 simple and 3 plumose setae on; dactylus with one simple terminally and 2 simple setae sub terminally; exopod present.

Pereiopod 1 ( Fig. 10 View FIGURE 10 , P 1 View FIGURE 1 ): B/R ratio and relative length of articles I to D not given, extremity broken after basis.

Pereiopod 2 ( Fig. 10 View FIGURE 10 , P 2 View FIGURE 2 ): B/R ratio 0.9, relative length of articles I to D: 3/23/25/17/31;

basis with 5 plumose and 2 simple setae; ischium unarmed; merus with 3 plumose setae; carpus with one plumose and 2 simple setae; propodus unarmed; dactylus with one terminal, 2 sub terminal and 2 lateral simple setae; exopod present.

Pereiopod 3 ( Fig. 11 View FIGURE 11 , P 3 View FIGURE 3 ): B/R ratio 1.6, relative length of articles I to D: 15/25/38/18/5;

basis with 3 plumose setae; ischium with 3 simple setae; merus with one simple and one plumose setae; carpus with one simple seta and 2 plumose setae; propodus with 2 simple setae distally; dactylus with one terminal simple seta and 2 simple setae sub terminally; exopod present.

Pereiopod 4 ( Fig.11 View FIGURE 11 , P 4 View FIGURE 4 ): B/R ratio 1.0, relative length of articles I to D: 14/25/39/17/6;

basis with 3 plumose setae; ischium with one plumose seta and 2 simple setae; merus with one plumose seta; carpus with one plumose seta and distally 2 simple setae;

propodus with 3 simple setae; dactylus with one strong simple seta terminally.

Pereiopod 5 ( Fig.11 View FIGURE 11 , P 5 View FIGURE 5 ): B/R ratio not given, basis damaged, relative length of articles I to D: 15/25/35/18/7; basis with 2 simple and 3 plumose setae; ischium with 2 strong simple setae; merus with one simple seta; carpus with one plumose seta and 2 strong simple setae; propodus with one strong simple seta; dactylus with one strong simple seta terminally.

Uropods ( Fig. 11 View FIGURE 11 , U), peduncle 1.2 times as long as pleotelson, 0.8 times as long as endopod, with 4 cuspidate setae along inner margin; exopod equal in length to endopod; endopod 2-articulated, basal article 1.4 times as long as distal article, with 4 cuspidate setae along inner margin; distal article with 4 cuspidate setae along inner margin, one terminal simple seta.

Male: adult male (ZMH K 64949 View Materials ), ( Fig. 12 View FIGURE 12 ) with pseudorostrum much shorter than in female and subadult male; teeth on dorsomedian line of carapace reduced; A2 flagellum not reaching pleon, peduncle with brush of setae along upper margin. Subadult male with 9 teeth along anterior margin of carapace, antennal notch absent; ventral margin finely serrate; dorsomediane line of carapace with 7 small teeth (irregularly arranged), pereionites 1–3 with dorsal teeth.

Distribution: Argentine Basin, 4602–4608 m.

Remarks:

Nine species are known so far from the genus Eudorellopsis :

E. biplicata Calman, 1912 View in CoL (N. Atlantic, N. Pacific; 20–1514 m); with 2 folds laterally on the carapace

E. deformis ( Kröyer, 1846) View in CoL (N. Atlantic, N. Pacific; 15–271 m); with short pseudorostrum

E. derzhavini Lomakina, 1952 View in CoL (NW Pacific; 28–390 m); with 2 folds laterally on carapace;

E. integra integra ( Smith, 1879) View in CoL (N Atlantic, N. Pacific; 1.5–1500 m); smooth, no teeth on carapace;

E. integra unadentata Vassilenko, 1990 (Arctic; 40–338 m); 1 dorsal tooth;

E. leuconi Vassilenko & Tzareva, 1990 View in CoL (W Pacific; 10–12 m); leuconid habitus, smooth, no tooth on carapace;

E. mykteros Gerken, 2016 View in CoL (SW Pacific; 1130–1264 m); 2 strong teeth dorsally;

E. longirostris Given, 1961 View in CoL ( California; 40–170 m); with 2 folds laterally on the carapace;

E. resima Calman, 1907 View in CoL ( New Zealand; 2–11 m); with one fold laterally on the carapace;

E. uschakovi Lomakina, 1955 View in CoL (NW Pacific; 85–412 m); with 2 folds laterally on the carapace, 1 dorsal tooth, 1 lateral tooth.

The genus is mainly living in the North Atlantic and Pacific in shallow water up to continental slope ( 1.5–1514 m).

The new species is the first described for the southwestern Atlantic.

The adult females in the new species have 7–9 teeth along the anterior margin of the carapace; the females can carry 1–2 weak lateral folds with teeth ( Figure 9c View FIGURE 9 ) running horizontally; there is only one species in this genus, E. biplicata Calman, 1912 , with 2 lateral folds on the carapace, but in E. biplicata the folds run more vertically. The short pseudorostrum in adult males is comparable to the pseudorostrum described for E. deformis .

The specimens belong to a new species because of 2 characters unique in the genus, 2 horizontal lateral serrated folds on carapace and 2 plus 3 pairs of mediodorsal teeth on carapace. In addition, the endopod is subequal in length to the exopod, when usually the endopod is shorter.