Protis perneti, Kupriyanova & Flaxman, 2024

Kupriyanova, Elena K. & Flaxman, Beth, 2024, Serpulidae (Annelida) of the Australian Indian Ocean Territories, Records of the Australian Museum (Rec. Aust. Mus.) 76 (4), pp. 211-242 : 227-228

Protis perneti n. sp.

urn:lsid:zoobank.org:act:0F6DE35C-270A-4093-9F9C-0AC49092D823

Fig. 9A–G

Material examined. Holotype: W.53467 (LK268), Territory of Christmas Island, Apollo Seamount (11°24'45"S, 104°56'32"E), depth 1285–1350 m, 13/07/2021 (prepared for SEM).

Paratypes: W.53480 (LK254), Territory of Christmas Island, Balthazar Seamount (11°24'16"S, 104°26'25"E), depth 1237–1290 m, 16/07/2021 (1 spec.) ; W.53482 (LK270), same locality (1 spec.) ; W.54384 (LK303), Cocos (Keeling) IslandsTerritory (11°49'56"S, 96°37'36"E), depth 1589–1896 m, 14/10/2022 (1 spec.) ; W.54408 (LK300), Cocos (Keeling) Islands Territory , Muirfield Seamount (13°16'41"S, 96°04'06"E), depth 1459–1595 m, 20/10/2022 (1 spec.) .

Description. Tube: white or slightly brownish, entirely opaque, circular in cross section, attached to substrate throughout its length. Tube surface with some growth lines, but without distinct ridges and peristomes ( Fig. 9a ).

Radioles: each lobe bearing 8–10 radioles arranged pectinately, not connected by an inter-radiolar membrane ( Fig. 9A ). Radiolar eyes and distinct long terminal pinnules absent.

Operculum: absent or lost in examined specimens ( Fig. 9A ).

Collar and thoracic membranes: collar with entire edge, short, barely covering radiolar lobes. Trilobed, medio-ventral lobe slightly higher and wider than lateral lobes ( Fig. 9B, C ); collar continuous with long thoracic membranes ending as long apron ( Fig. 9B, C ). Pairs of small, wart-like protuberances of collar chaetiger absent; tonguelets between ventral and lateral collar parts absent.

Thorax: with collar chaetiger and 6 uncinigerous chaetigers ( Fig. 9A–C ). Collar chaetae limbate and fin-and-blade, distal blade well separated from proximal dentate zone ( Fig. 9E ). Subsequent chaetae simple limbate, of two sizes. Apomatus chaetae present in posterior thoracic segments ( Fig. 9F ). Uncini along entire thorax saw-shaped, with 5–6 slightly curved teeth and simple pointed fang ( Fig. 9D ). Prostomial eyes not observed.

Abdomen: up to 40 abdominal chaetigers.Achaetous anterior abdominal zone absent. Uncini rasp-shaped, with 3-4 teeth in a row, 7–8 teeth in profile and simple pointed fang ( Fig. 9G ). Abdominal chaetae flat narrow geniculate with rounded teeth and tapered tip ( Fig. 9H ). Distinct long capillary chaetae of posterior chaetigers present. Posterior glandular pad not observed.

Size: total length up to 9.4 mm, including up to 3.6 mm long radioles, 2.8 mm long thorax, 3.0 mm long abdomen, width of thorax 0.9 mm. In holotype external diameter of tube mouth 1.2 mm, corresponding lumen diameter 1.0 mm.

Diagnostic remarks. According to World Register of Marine Species ( Read & Fauchald, 2024), the genus Protis contains seven poorly known species mainly from bathyal and abyssal locations. The taxonomy of the genus is problematic because the chaetae, uncini, and tubes are very similar and opercula, if present, are normally undifferentiated membranous vesicles. Both operculate and non-operculate species are described, however, soft vesicular opercula are easily lost. Moreover, Protis arctica (Hansen, 1879) and P. polyoperculata Kupriyanova, 1993a have been reported to contain both operculate and non-operculate specimens (Kupriyanova, 1993a; Ben-Eliahu & Fiege, 1996; Kupriyanova & Jirkov, 1997). Protis hydrothermica ten Hove & Zibrowius, 1986 shows two characters not known for the other species: warts between ventral and lateral collar lobes and a pair of pockets in the medio-ventral collar. Protis akvaplani Rzhavsky et al., 2013 shows very distinct characters: it has only six thoracic chaetigerous segments, short thoracic membranes ending after the 3rd thoracic chaetiger, and tube with a high longitudinal keel. Protis melmackenzieae n. sp. differs from all other species of the genus by very distinct pink tubes. Protis pacifica Moore, 1923 of Southern California (below 500 m) is recognisable because of its large size (body size up to 65 mm long). However, distinguishing Protis simplex Ehlers, 1887 and P. brownii ( Pixell, 1913) from P. perneti n. sp. is not straightforward because descriptions of the former two taxa are brief and generic, lacking indications of obvious diagnostic characters. Moreover, P. browni from Antarctica was even suggested as a possible synonym of P. simplex from the bathyal off Florida (ten Hove & Kupriyanova, 2009).

There are two obvious morphological differences between P. melmackenzieae n. sp. and P. perneti n. sp. First, the thoracic membranes are short ending at chaetiger 3 in the former but are with very long apron in the latter. Second, the distal blade of special collar chaetae is not separated from proximal dentate fin in P. melmackenzieae n. sp. versus very well separated in almost bayonet-like special collar chaetae of P. perneti n. sp.

With this in mind, we described here Protis perneti n. sp. as a species distinct from both nominal P. brownii and P. simplex mostly based on geographical information. This taxonomical decision will be tested in future molecular studies of deep-sea serpulids. This is one of the first newly described species of the genus in which a detailed illustrated description is accompanied by the molecular sequence data from the type series.

The results of the phylogenetic analysis ( Fig. 1 ) suggest that one of the terminals of P. perneti n. sp. is more closely related to Protis hydrothermica . Clearly, the relationships between these taxa need to be examined in further studies when additional specimens of the former species become available.

Etymology. The species is named after Professor Bruno Pernet (California State University at Long Beach, California, USA) for his important contributions to serpulid larval ecology and evolution.

Distribution. Only known from seamounts off Christmas and Cocos (Keeling) Islands, Indian Ocean, 1237–1896 m.

Figures

Figure 1. Maximum Likelihood consensus phylogram of the concatenated (18S and Cyt b) data set. Only nodes with bootstrap values> 70 are indicated. Nodes with bootstrap values 100 are indicated by *(asterisk).

Figure 9. Protis perneti n. sp. W.53467,A – general view of holotype without tube, a – holotype in tube, B – dorsal view of thorax showing length of thoracic membranes, C – lateral view of thorax, thoracic uncini, D – thoracic uncini, E – special collar chaetae, F – Apomatus chaeta, G – posterior abdominal uncini, H – abdominal chaetae. Scale: A, a – 1 mm, B, C – 0.5 mm, D, E, F – 10 µm, G, H – 5 µm.