Loimia poraporaensis, Hutchings & Daffe & Glasby & Lavesque, 2025

Loimia poraporaensis sp. nov.

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Figs 1A, B, D View FIGURE 1 ; 2C View FIGURE 2 ; 5 View FIGURE 5 ; 6 View FIGURE 6

Material examined. Holotype: AM W.51451, complete, some parapodia mounted for SEM, tissue sample taken for DNA studies, South Pacific , French Polynesia, Bora-Bora, 16.505 °S, 151.75 °W, collected P.A. Hutchings, by scuba in lagoon, 10 m, under dead Acropora spp. plate coral, Jan 2015 GoogleMaps . Additional material examined: UF005528 , Hawaii , Kaneohe Bay, off N tip of Mokapu base, 3–6 m outer reef slope, 21.76°N, 158.00°W, collected 30 th May 2017, BKON-2120 KANI-080 ( Fig. 2C View FIGURE 2 ), some parapodia used for molecular analyses GoogleMaps .

Description. Holotype complete, in two pieces, broken while extracting from flimsy tube made of pieces of coralline algae. Anterior part 75 mm in length and 12 mm in width (excluding buccal tentacles), with 17 pairs of notopodia plus 23 segments only with neuropodia; posterior part 130 mm in length, maximum width 5 mm with 97 segments, all with neuropodia. Posterior segments highly contracted. Pygidium circular, with glandular margins with slight indentations; anal papillae absent ( Fig. 5F View FIGURE 5 ). Preserved holotype yellowish, lacking pigmentation, with numerous buccal tentacles, most detached. Additional material complete, pinkish, 110 mm in length, maximum width 9 mm, excluding buccal tentacles. Both specimens robust and compact. Numerous deeply grooved buccal tentacles; short thin ones with reddish-purple bands, longer and thicker ones white ( Figs 2C View FIGURE 2 ; 5A–E View FIGURE 5 ). Ventral pads on live animal dark red, suggesting rich blood supply ( Fig. 2C View FIGURE 2 ). Pigmentation patterns lost after preservation.

Transverse prostomium attached to dorsal surface of upper lips, basal part lacking eye spots on both specimens. Peristomium forming lips; upper lip expanded, recurved and glandular; lower lip small and rectangular.

Three pairs of branchiae on segments 2–4, with short ridged main stem decreasing in length from 1 st to 3 rd pair, with numerous short branches, not aligned longitudinally, those on segment 2 inserted more dorsally than those on segment 3; 3 rd pair still more ventral ( Fig. 5C–E View FIGURE 5 ).

Nephridial papilla not seen on segment 3, presumably hidden by contracted branchiae. Genital papillae on segments 6 and 7, small, inserted posterior to base of notopodia. Neither specimens are gravid.

Dorsum smooth, with anteriorly transverse lines with weak vertical lines visible ( Fig. 5C View FIGURE 5 ). Segment 1 reduced dorsally, partially obscured by branchiae.

Lateral lobes on segments 1 and 3 ( Fig. 5B–D View FIGURE 5 ). Segment 1 with large, rectangular, glandular, elongate lateral lobes inserted more ventro-laterally than those on segment 3, margins slightly convoluted and thinner, connected across ventrum by raised narrow glandular ridge ( Fig. 5B View FIGURE 5 ). Segment 2 very narrow, covered laterally by lateral lobes of segment 3. Segment 3 with discrete lateral lobes, large elongate, rectangular with thinner convoluted anterior margins connected across ventrum. Segment 4 lacking lateral lobes ( Fig. 5B–D View FIGURE 5 ).

Ventral pads on segments 3–13 smooth, connected to raised glandular thoracic neuropodia, becoming more discrete and separated from neuropodia for rest of thorax after chaetiger 10, decreasing in width posteriorly; each pad divided into two by transverse line, each part with numerous vertical lines. Lacking mid-ventral streak or groove along both posterior thorax and abdominal segments ( Fig. 5B View FIGURE 5 ). Margins of buccal tentacles and notopodia Methyl Green stained, but not along ventrum ( Fig. 5A View FIGURE 5 ) and along margins of lateral lobes. Abdomen robust, with each segment well demarcated with slightly raised and slightly darker pigmented bands giving an almost striped pattern in vivo ( Fig. 2C View FIGURE 2 ) and also clearly visible on fixed material ( Fig. 5F View FIGURE 5 ).

Notopodia from segment 4, 17 pairs; 1 st pair aligned slightly more ventrally than subsequent ones, similarly aligned and of similar size, inserted at lateral margins of neuropodia, but forming a separate structure; all rounded and glandular, with pre- and post-chaetal lobes of similar size ( Fig. 5C, D View FIGURE 5 ). Notochaetae all simple capillaries with finely serrated margins, arranged in two graded tiers with shorter ones about ½ length of longer ones; notochaetae lacking microtexture visible under SEM ( Fig. 6A–B View FIGURE 6 ).

Neuropodia from segment 5 to pygidium; 1 st slightly shorter than all subsequent thoracic ones, slightly raised glandular with uncini arranged along entire length of podia. Neurochaetae initially arranged in single straight rows, then in double row back-to-back from segments 11–20, then again in single rows until body end. Thoracic uncini with 4+1 pectinate teeth ( Fig. 6C, D, G View FIGURE 6 ) and faint lateral striations. Abdominal neuropodia much shorter than thoracic neuropodia, becoming more elevated, as elongate rectangular structures, then less elevated toward posterior end, with far posterior ones almost sessile ( Fig. 5F View FIGURE 5 ); uncini arranged in slightly curved row ( Fig. 6E View FIGURE 6 ), with 4+1 pectinate teeth ( Fig. 6F, H View FIGURE 6 ).

Tube made of coral fragments, foraminiferans and calcareous fragments cemented together by a mucus sheath ( Fig. 2C View FIGURE 2 ), as seen in holotype and additional material.

Variation. Additional material from Hawaii closely resembles the holotype, with a very conspicuous blood-red anterior ventral pads and some banded buccal tentacles in live animal ( Fig. 2C View FIGURE 2 ). Given the geographical distance, we have not nominated the Hawaiian material as a paratype. However, COI sequences and morphology are very similar ( Fig. 9 View FIGURE 9 ), so we are confident that both specimens represent the same species.

Etymology. The species name refers to the type locality in the Tahitian language. Porapora (or Pōpora) was the island’s former name before it became Bora-Bora.

Type locality. Lagoon at Bora-Bora, Society Islands, French Polynesia.

Distribution. Bora-Bora, French Polynesia and Kaneohe Bay, Hawaii.

Habitat. Associated with living plates of Acropora spp. , on patch reefs within the reef lagoon at 10 m depth.

Remarks. Loimia poraporaensis sp. nov., is characterised by having a smooth dorsum and lateral lobes only on segments 1 and 3, which are compact without any dorsal flag-like extension. Live worms have both thin buccal tentacles with reddish- purple bands and thick buccal tentacles which are white, but this pigmentation is lost after preservation. It can be separated from L. aimehoensis sp. nov., which has buccal tentacles with transverse reddish bands and many small white spots when alive; lateral lobes on segments 1 and 3, those on segment 1 large semi-circular glandular lobes connected mid ventrally ( Fig. 3B View FIGURE 3 ) and those on segment 3 extending dorsally to cover bases of branchiae and with a flag-like extension, and terminating laterally at margins of ventral pads and ventral pads well developed and segmentally demarcated from segment 2 to 19. They also differ in the dentition of thoracic uncini being 4+ 1 in L. poraporaensis sp. nov., and 5+1 for L. aimehoensis sp. nov., and in the notochaetae. The two tiers of notochaetae differ less in length in L. aimehoensis sp. nov., (shorter ones about 2/3-3/4 length of longer ones vs. shorter ones about ½ length) vs L. poraporaensis sp. nov., (shorter ones about ½ length). This latter character has rarely been used to distinguish species of Loimia but may be useful, along with other morphometric and meristic chaetal characters. The lack of bright white spots on the buccal tentacles of L. poraporaensis sp. nov., whereas they are present in L. aimehoensis sp. nov., is another character which has not previously been reported, although many descriptions lack details of colouration of tentacles.

The lack of any dorsal tubercles clearly separates the two new species ( L. aimehoensis sp. nov. and L. poraporaensis sp. nov.) from L. tuberculata Nogueira, Hutchings & Carrerette, 2015 , L. keablei Nogueira, Hutchings & Carrerette, 2015 , and L. verrucosa ( Caullery, 1944) , all inhabiting coral-reef habitats except for the latter, which was collected at Saleyer-anchorage [Selayar Island, off Sumatra], Indonesia by dredge at 36 m depth, likely among coral patches ( Table 2 View TABLE 2 ). Loimia triloba Hutchings & Glasby, 1988 was also collected from muddy to medium coarse sands associated with inter-reefal habitats on the Great Barrier Reef, Queensland and also lacks dorsal tubercles ( Table 2 View TABLE 2 ). The two new species both lack lateral lobes on segment 4, a character shared with L. lanai Hutchings, Daffe, Flaxman, Rouse & Lavesque, 2024 , L. ochracea ( Grube, 1877) , L. batilla Hutchings & Glasby, 1988 , L. ingens ( Grube, 1878) and perhaps L. nigrifilis Caullery, 1944 although Caullery does not illustrate any lateral lobes, and his description does not mention any on segment 4 ( Table 2 View TABLE 2 ). Several species included in Table 2 View TABLE 2 have fairly vague descriptions with limited figures, such as L. ingens ( Grube, 1878) , L. nigrifilis Caullery, 1944 ; L. ochracea ( Grube, 1877) and L. verrucosa Caullery, 1944 ; thus, further research is required to allow more precise comparisons. The description of L. ingens is based on material described by Hutchings & Glasby (1988) based on Australian material and not from the type locality.

Loimia lanai has a lateral lobe on segment 3 with a dorsal flag-like extension, similar to L. aimehoensis sp. nov., but has a mid-ventral groove on the abdomen which is absent in the latter species. Loimia batilla and L. ingens have lateral lobes on segments 1, 2 and 3, whereas all the other species in Table 2 View TABLE 2 , have them only on segments 1 and 3. Loimia batilla has large scoop-like lobes on segment 1 whereas L. aimehoensis sp. nov., has large oval-shaped lobes and L. poraporaensis sp. nov., has large rounded lobes with thickened margins connected mid ventrally by a narrow ridge. Other species, such as L. juani Nogueira, Hutchings & Carrerette, 2015 and L. pseudotriloba Nogueira, Hutchings & Carrerette, 2015 , have lateral lobes on segments, 1, 3 and 4 unlike our two new species. Loimia nigrifilis has the first pair of branchiae with spirally arranged branches, instead of dichotomously as in L. poraporaensis sp. nov. and L. aimehoensis sp. nov. However, having only illustrations of the posterior end (with an attached copepod) and an uncinus ( Caullery, 1944), it is difficult to compare it with other species with lateral lobes on segments 1 and 3. We assume that the reference to lateral lobes on segment 2 actually refers to those on segment 1, and while the lobes on segment 3 are described as very large, there are no descriptions of lobe shape or extent. This author also described a white glandular band that surrounds the base of branchiae and the first 6–7 notopodia, as well as very long buccal tentacles with transverse annulations and dark, almost black bands.

The holotype of Terebella ochracea Grube (1877) , a species from Mermaid Cove in Western Australia currently accepted as Loimia ochracea ( Grube, 1877) ( Read & Fauchald, 2024) , is in poor condition, but shows lateral lobes only on segments 1 and 3 ( Hutchings & Glasby, 1988). Further analyses of numerous specimens from both Western Australia and the Northern Territory —all from intertidal to shallow sub-tidal muddy and sandy sediments, confirmed the presence of lateral lobes only on segments 1 and 3 and the absence of any tubercles ( Hutchings 1997) which clearly separate this species from our two new ones. Loimia ochracea has all branchiae aligned in a vertical row, whereas both L. aimehoensis sp. nov., and L. poraporaensis sp. nov., do not have their branchiae vertically aligned.

Other species described from adjacent to the study region include Loimia macrobranchia Wang, Sui, Kou & Li, 2020 described from the South China Sea. Although the description does not provide habitat data, the region is considered to be too far north for extensive coral reefs and, therefore, not compared or discussed further. In comparison, L. bandera Hutchings, 1990 was described from dredged soft sediment from Hong Kong harbour, similar to the habitat of L. triloba , which we consider inter-reefal; therefore, both species are included in the key below.

Finally, colour patterns can be useful for distinguishing between species, although this character has not been recorded for most of the species listed in Table 2 View TABLE 2 .