Bathycuma squamosa Muhlenhardt-Siegel 2005

Bathycuma squamosa Mühlenhardt-Siegel, 2005

(Figures 4–7)

Material. DIVA II, EBS #41-S: 1 male (damaged posterior to pereionite 2, pleon broken off after pleonite 3, Fig. 4)) ZMH: K-43912; DIVA II, EBS #63-S: 1 subadult male (only carapace and free thoracic segments, dissected), 1 non-ovigerous female, 1 manca ZMH: K-43913; BIOZAIRE 3, KGS #81: 1 s pent female MNHN-IU-2012-1352; BIOZAIRE 3, KGS #78: 1 non-ovigerous female (dissected) MNHN-IU-2012-1353.

Description. Subadult male (ZMH: K-43913)

Antenna 1 (Fig. 5, A1): relative length of peduncle articles 1 to 3: 42/29/29.

Maxilliped 2 (Fig. 5, Mxp2): B/R ratio 1.3, relative length of articles I to D: 11/23/28 /23/15.

Maxilliped 3 (Fig. 5, Mxp3): B/R ratio not given, basis damaged during dissection, relative length of articles I to D: 10/23/27 /22/17.

Pereiopod 1: broken, exopod present; not figured.

Pereiopod 2 (Fig. 5, P2): B/R ratio 0.9, relative length of articles I to D: 2/ 22/31/10 /35.

FIGURE 3. Cyclaspoides longimerus, male; P2: pereiopod 2; P3: pereiopod 3; P4: pereiopod 4; P5: pereiopod 5; U: pleotelson and right uropod; scale bars: 0.1 mm (P2, P3, P4, P5) and 0.5 mm (U).

Pereiopod 3 (Fig. 5, P3): B/R ratio not given, basis damaged during dissection, relative length of articles I to D: 15/21/ 38/15/11.

Pereiopod 4 (Fig. 5, P4): B/R ratio not given, basis damaged during dissection, relative length of articles I to D: 14/20/ 42/13/11.

Pereiopod 5: broken, not figured.

Pleotelson (Fig. 5, U)1.9 times as long as wide; 1.4 times longer than uropod peduncle.

Manca (ZMH: K-43913). Uropod, peduncle shorter than exopod; exopod 1.5 times longer than bi-articulated endopod; endopod basal article 1.7 times longer than distal article.

Spent female (MNHN-IU-2012-1352; bad condition due to fixation/conservation in formalin), 8.3 mm long.

Carapace oval, similar to Atlantocuma; pseudorostral lobes meeting for a short distance in front of ocular lobe; siphonal tube only slightly protruding; ocular lobe elongated; eyes missing.

Antennal notch distinct, reaching level of anterior margin of frontal lobe; anterolateral tooth acute; anteroventral margin of carapace smooth. Integument translucent, most probably due to fixation.

Five free thoracic segments visible.

Pleon 1.2 times as long as carapace and free thoracic segments combined.

Pleotelson elongate, 1.9 times as long as wide, produced between the uropods, longer than peduncles; each anal valve with three to four hair-like setae at distal tip.

Non-ovigerous female (ZMH: K-43913). Antenna 1 (Fig. 6, A1): relative length of peduncle articles 1 to 3: 50/ 23/27; article 1 with one simple seta, article 2 with three simple setae, article 3 with two simple setae; accessory flagellum minute with three simple setae terminally; main flagellum bi-articulated, with two aesthetascs, one long and four short simple setae.

Maxilliped 2 (Fig. 6, Mxp2): B/R ratio 1.7, relative length of articles I to D: 5/29/27 /24/15; basis with fringe of setae along inner margin, distally five pappose setae; merus with one pappose seta; carpus and propodus each with one pappose and two simple setae, propodus with a further minute simple seta; dactylus with a strong terminal seta (unguis) and a hair-like seta.

Maxilliped 3 (Fig. 6, Mxp3): B/R ratio 1.9, relative length of articles I to D: 15/17/25/23/20; basis with fringe of setae along inner margin and seven pappose setae; ischium with short pappose seta; merus with a distal tooth, a simple and a pappose seta; carpus with four simple setae; propodus with three simple setae, dactylus with a longitudinal fringe of setae along inner margin and a strong terminal seta which is longer than dactylus; exopod present.

Pereiopod 1 (Fig. 6, P1): B/R ratio not given, broken off after basis which bears one pappose and eight simple setae; exopod present.

Pereiopod 2 (Fig. 6, P2): B/R ratio 0.8, relative length of articles I to D: 7/22/23 /8/40; basis with a simple and a pappose seta; merus with five simple setae; carpus with two simple and two strong serrulate setae; dactylus with five teeth and a strong terminal (broken) and six simple setae; exopod present.

Pereiopod 3 (Fig. 7, P3): B/R ratio 1.3, relative length of articles I to D: 11/22/41 /14/12; basis with two pappose setae; ischium with a short pappose and two long terminally annulated setae; merus with a long terminally annulated seta; carpus with three long terminally annulated setae; propodus with two long terminally annulated setae; dactylus with one terminally annulated seta; exopod present.

Pereiopod 4 (Fig. 7, P4): B/R ratio 0.6, relative length of articles I to D: 14/ 20/47/11 /8; basis with a long pappose seta; ischium with a long broken seta; merus with a short hair-like and a long terminally annulated seta; carpus with three hair-like and four strong simple setae; propodus with a tooth and three long terminally annulated setae; dactylus with a strong terminal seta (unguis).

Pereiopod 5 (Fig. 7, P5): B/R ratio 0.3, relative length of articles I to D: 12/20/47 /12/9; basis with pappose, terminally annulated seta; carpus with short simple seta; propodus with a long simple and a long terminally annulated seta; dactylus with a strong terminal seta shorter than dactylus and two hair-like setae.

Uropod (Fig. 7, U): peduncle nearly as long as exopod and 1.3 times as long as endopod; exopod 1.3 times as long as endopod, basal article 1.3 times longer than distal; endopod clearly shorter than exopod, bi-articulated, basal article with three stout, four tiny and terminally a longer cuspidate setae along inner margin, 1.4 times as long as distal article, which has four cuspidate setae along inner margin and two longer terminally.

Distribution. Angola, Cape and Guinea Basins, 5047–5395 m depth.

Remarks. The specimens from the Cape and Guinea Basins are very similar to Bathycuma squamosa Mühlenhardt-Siegel, 2005a due to the habitus, especially the rough carapace surface, and the single row of dorsomedian teeth. Unfortunately, the male from the Cape Basin has the pleon with the uropods broken off after pleonite 3, but pleonites 1 to 3 do have developing pleopods.

The subadult male from the Guinea Basin has a developing antenna 2 but is broken after pereionite 4; pereiopods 1 to 3 bear exopodites. The carapace of this specimen is slightly more elevated in the anterior region than in the juvenile male from the Angola Basin. The two mancas from the Guinea Basin have their uropod peduncle at least equal in length to the pleotelson, which is rather long, as described for B. squamosa from the Angola Basin. The pereiopod 2 propodus and basal part of dactylus are not serrated in the present specimen but in the male described from the Angola Basin.

The two specimens from the Ifremer collection are strongly decalcified.

Comparing the females with the male holotype of B. squamosa and the males from the Cape and Guinea Basins, the antennal notch is more pronounced in the female (small in the male); the dorsomedian serration or teeth on the carapace which are clearly visible in the male are not discernable in the female, maybe due to decalcification. The structure of the integument of the pleotelson is scaly in the female, in B. squamosa from the Angola Basin it is clearly serrated but smooth in the manca from the Guinea Basin. Again this difference could be caused by decalcification or developmental stage, respectively. The carapace is stronger elevated dorsally and the lateral carina is not discernable in the females, whereas the carapace has no clear dorsal elevation, but the lateral carina is clearly discernable in the male of B. squamosa. The extremities of the female are very close to the male, even the serration or teeth on the propodus and basal part of the dactylus of the pereiopod 2 are visible in the female.

Species similar to the females of B. squamosa in the Ifremer collection with regard to the subrostral tooth are B. elongatum Hansen, 1895 (Cape Verdes, 4980 m) and B. natalensis Stebbing, 1912 (S and W Africa, 15–410 m).

In B. elongatum and B. natalensis the uropod rami are shorter than the peduncle (in B. squamosa female at least the exopod is longer than the peduncle). The exopod in the female of B. squamosa is clearly longer than the endopod (equal in length in B. elongatum, not discernable in B. natalensis as the endopod is broken off in the described specimen).

In the female of B. squamosa the pleotelson is longer than the uropod peduncle like also in B. squamosa male and B. capense (Zimmer 1921). B. capense has a short pseudorostrum and the anterior margin of the carapace has a steep vertical direction in the subadult males and a very shallow antennal notch. However, the female of B. squamosa has an elongated pseudorostrum, the anterior carapace margin is directing ventro-posteriorly, the subrostral tooth is distinct, and the antennal notch reaches well beyond level of the ocular lobe.