Cyanea altafissura, Samsodien, 2024

Samsodien, Yusra, 2024, Integrative taxonomy reveals the presence of a new species of Cyanea (Scyphozoa: Discomedusae: Semaeostomeae: Cyaneidae) from the West coast of Africa, Zootaxa 5507 (3), pp. 401-426 : 407-412

Cyanea altafissura sp. nov.

[ TABLE 3 ; FIGURES 4–10 ]

Material examined. Holotype: Ghana: Gulf of Guinea (29.5cm in diameter, 15 August 2019, in 7% formaldehyde in ambient seawater, area (4°N, 2°W), SAMC-A096867 ) . Paratypes: Ghana: Gulf of Guinea (23.3 cm in diameter, 12 August 2019, preserved in 7% formaldehyde in ambient seawater, area (5°N, 0°W), SAMC-A096868 ) ; Côte d'Ivoire: Gulf of Guinea (22.2 cm in diameter, 4 August 2019, preserved in 7% formaldehyde in ambient seawater, area (4°N, 5°W), SAMC-A096869 ) .

One specimen collected by the RV Dr. Fridtjof Nansen off Côte d'Ivoire on the 6 th of August 2019 by bottom trawl at a sampling depth of 23 m (5.12°N, 4.75°W) ; Four specimens collected by the RV Dr. Fridtjof Nansen off Ghana on the on the 12 th of August 2019 by bottom trawl at a depth of 28 m (5.05°N, 0.94°W) ; Three specimens collected by the RV Dr. Fridtjof Nansen off Accra off Ghana on the 13 th of August 2019 by bottom trawl at a depth of 26 m (5.39°N, 0.36°W) ; Two specimens collected by the RV Dr. Fridtjof Nansen off Axim Ghana on the 9 th of August 2019 by bottom trawl at a depth of 41 m (4.80°N, 2.30°W) ; Four specimens collected by the RV Dr. Fridtjof Nansen off Akwidaa, Ghana, on the 15 th of August 2019 by bottom trawl at a depth of 26 m (4.72°N, 2.03°W) ; One specimens collected by the RV Dr. Fridtjof Nansen off Assouindé, Côte d'Ivoire on the 8 th of August 2019 by bottom trawl at a depth of 25 m (5.13°N, 3.44°W) ; Four specimens collected by the RV Dr. Fridtjof Nansen off Takoradi, Ghana on the 10 th of August 2019 by bottom trawl at a depth of 26 m (4.82°N, 1.78°W) ; One specimen collected by the RV Dr. Fridtjof Nansen off Akrou, Côte d'Ivoire on the 7 th of August 2019 by bottom trawl at a depth of 25 m (5.19°N, 4.34°W) ; Four specimens collected by the RV Dr. Fridtjof Nansen off Gazéko, Côte d'Ivoire on the 5 th of August 2019 by bottom trawl at a depth of 23 m (5°N, 5.73°W) ; Two specimens collected by the RV Dr. Fridtjof Nansen off New Town , Ghana on the 8 th of August by a bottom trawl at a depth of 26 m (5.05°N, 3.08° W) ; One specimen collected by the RV Dr. Fridtjof Nansen off Akwidaa, Ghana on the 8 th of August 2019 by bottom trawl at a depth of 25 m (4.59°N, 2.03° W) ; One specimen collected by the RV Dr. Fridtjof Nansen off Kanga, Ghana on the 28 th of September 2019 by pelagic trawl at a depth of 33 m (4.94°N, 2.68° W) ; One specimen was collected by the RV Dr. Fridtjof Nansen off Nyanga, Gabon, on the 26 th of September 2017 by bottom trawl at a depth of 41 m (3.06°S, 10.04°E) ; One specimen was collected by the RV Dr. Fridtjof Nansen off Gabon on the 25 th of September 2017 by trawl at a depth of 46 m (2.48°S, 9.39°E) ; One specimen was collected by the RV Dr. Fridtjof Nansen off Gabon, on the 24 th of September 2017 by bottom trawl at a depth of 118 m (2.57°S, 9.06°E) ; One specimen was collected by the RV Dr. Fridtjof Nansen off Nyanga, Gabon, on the 26 th of September 2017 by bottom trawl at a depth of 41 m (3.06°S, 10.04°E) ; Four specimens were collected by the RV Dr. Fridtjof Nansen off the coast of Angola, on the 16 th of October 2017 by pelagic trawl at a depth of 20 m (10.11°S, 13.34°E)

Type locality. Akwidaa, Ahanta West Municipal District, Ghana

Distribution. Range extends around the Gulf of Guinea, West Africa, from Côte d’Ivoire to Gabon and southwards to central Angola.

Diagnosis. Medium-sized Cyanea ; exumbrella surface slightly papillose throughout; 16 rectangular marginal lobes; rhopalial clefts deeper than velar clefts; radial and coronal muscle fields prominent, without gastrovascular intrusions, with 5 and 7 muscle folds respectively. With up to 200 strap-like, hollow tentacles arranged in eight Ushaped fields or clusters. Rhopalium small; statocyst on short stalk lacking bulbs/warts located at base of long, tubular rhopalial pit. Mouth arms greatly thickened basally; gastrovascular sinus in 16 lobes separated by interrupted septa of the nozakii type, penetrating marginal lappets on a broad front as a fine network of branching and anastomosing canals.

Biological data: Found at depths between 20–118 m.

Etymology. altafissura, Latin , refers to the comparatively deep depth of the rhopalial cleft.

Holotype description. Umbrella a flattened hemisphere with a diameter of 295 mm; thickest centrally and thinning to margin. Exumbrella light brown in colour, with nematocyst warts that impart a rough surface texture throughout (papillose). Umbrella margin divided into 16, broad and approximately quadratic lappets, 44.8 mm in width; two lappets per octant; (secondary) clefts between rhopalial lappets deeper than those between (primary) velar lappets. Coronal muscle in 16 fields, rhopalial fields (9.8 mm) narrower than velar (18.4 mm) fields; each field separated from neighbour by prominent thickened septal ridge; fields with 7–11 coronal muscle folds. Radial muscles in 16 fields extending distally from coronal muscles to bell margin, not into lappets, each field with 3–6 muscle folds. Coronal and radial muscles without gastrovascular pits. With eight rhopalia, each situated at base of long pit, protected by margins of neighbouring lappets; statocyst at end of short, smooth rhopalial stalk, which lacks a basal bulb. Eight, deep adradial U-shaped tentacle bundles situated between radial muscle fields opposite velar lappets; tentacle bundles comprised of three rows of tentacles proximally but a single row distally; tentacle bundles span the entire length of the radial muscle fields; tentacles hollow, between 160–190 in number, largest proximally and smallest distally. Mouth broadly quadratic with four oral arms, thickened at base; thin, curtain-like tissue extending between oral arms; shorter than the bell diameter. Central stomach without septa or gastric cirri; extending to bell margin as 16 gastric pouches, separated by interrupted septa of the nozakii type, penetrating lappets on a broad front as dendritic canals, with obvious anastomoses. Gonads complexly folded, cream in colour, pendulous; attached to the subumbrella.

Description of other specimens and additional data

Medusae: The bell colour was light brown or beige, although one specimen had purple oral arms and gonads. Bell a flattened saucer; thicker at the centre and thin at the periphery; maximum bell thickness increasing with increasing bell diameter ( Table 3 ). Exumbrella surface texture slightly rough throughout ( Figure 4 ). Bell margin divided into 16 broad, rectangular lappets of approximately similar size and shape ( Figure 5 ); lappet width increases isometrically with bell diameter; each approximately 16% bell diameter in width; the depth of the (primary) velar and (secondary) rhopalial marginal clefts increases with increasing bell diameter ( Table 3 ), isometric; standardised depth of rhopalial clefts (mean = 0.09, SE = 0.006, n = 22) significantly deeper than velar clefts (mean = 0.06, SE = 0.005; n = 22) (F = 17.012, p = 0.0005). Only four of the thirty-eight analysed individuals (~10%) had tertiary clefts, dividing the bell margin into 32 marginal lobes.

Rhopalium relatively small; statocyst on a short, smooth stalk lacking basal bulbs, papillae or other protuberances ( Figure 6 ); located at the base of long tube-like pit, bounded on the exumbrella surface by a hood formed from the fusion of neighbouring lappet edges, and on the subumbrella surface by overlapping lappet margins ( Figure 6 ); ocelli not observed.

Sixteen coronal muscle fields, each field separated from neighbour by prominent thickened septal ridge ( Figure 7 ); rhopalial fields (mean = 4% bell diameter, SE = 0.2%, n = 68) significantly narrower than velar (mean = 7.2% bell diameter, SE = 0.2%, n = 67) (F = 182.86, p <0.0005). Number of muscle folds per field varying from between 4–14 (mode = 7) in a size independent way, as too does the depth of individual muscle folds (mean = 6.5 mm, SE = 0.1 mm). Radial muscles in 16 fields, extending from a position between rhopaliar and velar coronal muscles towards base of lappets at bell margin ( Figure 7 ); with between 3–8 muscle folds (mode = 5) proximally, fanning out to a greater number distally. Gastrovascular pits in the coronal and radial muscle folds absent.

Tentacles arranged in eight, deeply rectangular, U-shaped bundles that extend from distal edge of coronal muscles towards base of lappets ( Figure 7 ); tentacle bases very close to each other, and distinct rows hard to observe clearly, especially proximally. As a rule, tentacles in a single row towards bell margin and clustered in up to four rows adjacent to coronal muscle fields. Tentacles hollow, strap-like ( Figure 7 ) and with a clear endodermal core. Proximal tentacles longer and thicker than distal ones. Up to 200 tentacles per field, size dependant.

The mesoglea at the base of the manubrium a strongly thickened ring ( Table 3 ) supporting four oral arms on short pillars ( Figure 8 ); oral arms greatly expanded laterally, membranous and curtain-like. Unfortunately, it was not possible to accurately measure oral arm length, but generally shorter than diameter of bell. Mouth approximately quadratic in shape; stomach without septa; small specimens with numerous short gastric cirri arranged in four inter-radial groups attached to subumbrella ( Figure 9 ). Stomach extending to bell margin as 16 gastric pouches that penetrate lappets on a broad front as a network of fine dendritic canals, with obvious anastomoses ( Figure 5 ); pouches separated by indistinct septa distal of coronal muscle fields that are interrupted and of the nozakii- type ( Figure 10 ) with anastomosing connections between the tentacular and rhopalial gastrovascular pouches. Four, complex, folded gonads originate from stomach wall, and emerge from between the thickened bases of adjacent oral pillars ( Figure 8 ) to hang freely below subumbrella, decumbent.

Figures

FIGURE 4. Cyanea altafissura sp. nov. a) Exumbrella surface showing uniform distribution of nematocyst warts.

FIGURE 5. Cyanea altafissura sp. nov. View of subumbrella showing rectangular shape of marginal lappets, the comparative depths of the primary/velar (pmc) and secondary/rhopalial (smc) clefts, and the dendritic and anastomosing nature of marginal canals.

FIGURE 6. Cyanea altafissura sp. nov. A) Subumbrella view of the bell margin, showing a secondary marginal cleft (smc), the position of radial muscle fields (rmf), the rhopalium (r) and the overlapping edges of the marginal lappets that in effect form a rhopalial tube (see schematic inset). B) subumbrella view of bell margin showing a secondary marginal cleft (smc) and the rhopalial hood (rh). C) detail of rhopalium at base of rhopalial “tube”, note the absence of bulbs/papillae on stalk.

FIGURE 7. Cyanea altafissura sp. nov. Subumbrella view of U-shaped tentacular bundle (tb), hollow tentacle (t), velar (vcmf) and rhopalial (rcmf) coronal muscle fields, radial muscle fields (rmf), primary marginal cleft (pmc) and rhopalium (r).

FIGURE 8. Cyanea altafissura sp. nov. Subumbrella view showing one of the four gonads (g) emerging from between adjacent oral pillars (op) at base of oral arms (oa). Velar (vcmf) and rhopalial (rcmf) coronal muscle fields, radial muscle fields (rmf) and tentacle bundles (tb) also shown.

FIGURE 9. Cyanea altafissura sp. nov. Subumbrella view, showing coronal muscle fields and inter-radial gastric cirri.

FIGURE 10. Cyanea altafissura sp. nov. Subumbrella view of gastric sinus running beneath radial muscle fields (rmf) and tentacular bundle (tb), highlighted by red dye. Inset shows point of dye injection (circle) and subsequent movement through anastomosing connections between the tentacular and rhopalial gastrovascular pouches.