Branchinotogluma Pettibone 1985
Creators: name: Lee, Won-Kyung
name: Kim, Se-Joo
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Phyllodocida
Polynoidae
Branchinotogluma

description: GenusBranchinotoglumaPettibone, 1985
Branchinotogluma bipapillata Zhou, Wang, Zhang & Wang, 2018: 528–533, figs 1–7; table 1.
Material examined.
Indian Ocean • 2 ♂; Cheoeum; 12°37.1'S, 66°07.6'E; depth 3018 m; 28 Mar. 2023; W-K Lee leg.; hydrothermal vent; GenBank: PP 600168 – PP 600169; KRIBB 310101 to KRIBB 310102 • 2 ♂, 2 ♀, 1 undetermined; Onnuri; 11°24.9'S, 66°25.4'E; depth 2009 m; 1–2 Apr. 2023; W-K Lee leg.; hydrothermal vent; GenBank: PP 600170 – PP 600174; KRIBB 310103 to KRIBB 310107 • 1 ♀, 2 undetermined; Onnare; 9°47.4'S, 66°41.9'E; depth 2993 m; 3 Apr. 2023; W-K Lee leg.; hydrothermal vent; GenBank: PP 600175 – PP 600177; KRIBB 310108 to KRIBB 310110 • 1 ♂, 1 ♀; Onbada; 9°48.9'S, 66°40.6'E; depth 2563 m; 4 Apr. 2023; W-K Lee leg.; hydrothermal vent; GenBank: PP 600178 – PP 600179; KRIBB 310111 to KRIBB 310112 • 2 ♂, 2 ♀; Saero; 11°19.7'S, 66°26.9'E; depth 3256 m; 7 Apr. 2023; W-K Lee leg.; hydrothermal vent; GenBank: PP 600180 – PP 600183; KRIBB 310113 to KRIBB 310116.
Description.
Specimens relatively well preserved, with 21 segments, 12.0–51.0 mm in length and 5.0– 16.6 mm in width. Body shape fusiform, tapered anteriorly and posteriorly (Fig. 2 A, B, Table 2). Pairs of elytra on elytrophores on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, and 19; elytra oval to subreniform, white, slightly transparent, with a smooth surface (Fig. 2 C – E). Dorsal cirri on segments 3, 6, 8, 10, 12, 14, 16, 18, 20, and 21, extending beyond the tips of neurochaetae. Branchiae arborescent; grouped in two, one at base of the notopodia and another at base of dorsal tubercles or elytrophores; starting from segment 3 and ending between segments 18 or 21 (Table 2).
* Observed in a single specimen (KRIBB 310108; Fig. 2 G).
Prostomium bilobed, triangular anterior lobes with slender frontal filaments (Fig. 2 F). Median antennae on anterior notch, with a cylindrical ceratophore and subulate style; palps thick, smooth, and end in subulate tips; lateral antennae and eyes absent (Fig. 2 F). Tentacular segment fused to prostomium, with pair of tentacular cirri on each side, and a small acicular lobe at the base of tentaculophore; tentacular cirri slender (Fig. 2 F).
First segment not distinct, fused to prostomium. Pharynx with five dorsal and four ventral papillae in one immature individual, but not seen in others (Fig. 2 G). Second segment with first pair of elytrophores, ventral cirri, and biramous parapodia. Third segment with ventral cirri and first pair of branchiae. Fourth to last segments with ventral cirri and biramous parapodia. Notopodia smaller than neuropodia; notochaetae stout, few, arranged in radiating bundles; neurochaetae slender, numerous, forming a fan shape (Fig. 2 H – K).
Sexual dimorphism evident. In males, posterior segments modified (Fig. 3 A) with 10 th elytra and elytrophores much smaller than 9 th (Figs 2 D, 3 A, Table 2); ventral papillae present on segments 12–13, long, tapering, with slender tips extending to next segment; ventral lamellae on segments 14–17, round (Fig. 3 B). In females, posterior segments not modified (Fig. 3 C), with 10 th elytra and elytrophores similar to 9 th (Figs 2 E, 3 C, Table 2); ventral papillae present on segments 11–15, short and blunt (Fig. 3 D).
Distribution.
Indian Ocean (depth 1732–3256 m): Longqi and Duanqiao vent fields on the southern Southwest Indian Ridge; Tiancheng vent field on the northern Southwest Indian Ridge; Edmond vent field on the southern Central Indian Ridge; Onnare, Onbada, Saero, Onnuri, and Cheoeum vent fields on the northern Central Indian Ridge.
Remarks.
Comparisons of key morphological characters between the geographically distant populations are present in Table 2. The key characters of the nCIR specimens of B. bipapillata largely correspond with those of the SWIR specimens (Zhang et al. 2018). However, the two populations differ in the last segment with branchiae in females (segment 19 in sSWIR compared with segment 18 or 21 in nCIR; Table 2).
Among the 16 specimens from the nCIR population, 10 specimens with body length greater than 20 mm were well-developed in all features indicating adult morphology, while characters of sexual dimorphism were not observed in 6 specimens shorter than 20 mm.
DNA barcoding and phylogenetic analysis.
Partial sequences of CO 1, 16S, and 18 S were recovered from 16 specimens collected from the nCIR. As shown in Table 1, 48 newly obtained sequences have been deposited in GenBank.
In CO 1, the mean intra-population variation was 0.56 % for nCIR and 0.65 % for SWIR, with an inter-population variation of 1.00 % (Table 3). In 16 S, the mean intra-population variation was 0.27 % for nCIR and 0.33 % for SWIR, with an inter-population variation of 0.39 %. In 18 S, the mean intra-population variation was 0.01 % for nCIR and 0.00 % for SWIR, with an inter-population variation of 0.004 %.
* not calculated.
The interspecific variation between B. bipapillata and other congeners ranged from 18.63 % to 21.88 % in CO 1, and from 13.11 % to 19.08 % in 16 S (Suppl. material 1: table S 2). In 18 S, the interspecific variation ranged from 1.69 % to 3.80 %.
The maximum likelihood phylogenetic tree, constructed with concatenated sequences of CO 1, 16S, and 18 S (Fig. 4), shows the SWIR and nCIR populations of B. bipapillata clustering together as a single clade, indicating no significant divergence between populations from different ridges. Within the Branchinotogluma genus, B. bipapillata is closely related to a clade including B. kaireiensis, B. pettiboneae Wu et al., 2019, and B. robusta Wu et al., 2023.
description: Published as part of Lee, Won-Kyung & Kim, Se-Joo, 2024, Distribution extension of a vent scale worm Branchinotogluma bipapillata (Polychaeta, Polynoidae) in the Indian Ocean, pp. 139-149 in ZooKeys 1215 on pages 139-149, DOI: 10.3897/zookeys.1215.129623