Hyalopomatus nogueirai, Kupriyanova & Flaxman, 2024

Hyalopomatus nogueirai View in CoL n. sp.

urn:lsid:zoobank.org:act:7BFB27A6-D9F1-43B1-83A9-EF16AC0B89A7

Fig. 10A–I View Figure 10

Material examined. Holotype: W.55296 (LK302), Cocos (Keeling) Islands Territory , Rudist Seamount (11°03'47"S, 99°26'36"E), depth 3780–3839 m, 12/10/2022 (specimen with operculum in tube). GoogleMaps

Paratypes: W.53396 (LK252), Christmas Island SE (10°33'00"S, 105°42'11"E), depth 1225–1626 m, 06/07/2021 (1 spec.); W.55297 (LK288), Cocos (Keeling) Islands Territory, Muirfield Seamount (13°14'32"S, 96°17'31"E), depth 932–965 m, 21/10/2022 (1 spec.); W.55295 (LK281), Christmas Island Territory, Balthazar Seamount (11°21'33"S, 104°2'53"E), depth 3510–3611 m, 7/10/2022 (1 spec.); W.54396 (LK279), Cocos (Keeling) Islands Territory, Rudist Seamount (11°03'47"S, 99°26'36"E), depth 3780–3839 m, 12/10/2022 (1 spec.); W.55300 (LK301), Cocos (Keeling) Islands Territory, Muirfield Seamount (13°16'41"S, 96°04'06"E), depth 1459–1595 m, 20/10/2022 (1 spec. prepared for SEM); W.55293 (LK272), Cocos (Keeling) Islands Territory, Rudist Seamount (11°03'47"S, 99°26'36"E), depth 3780–3839 m, 12/10/2022 (1 spec.); W.54368 (LK291), Cocos (Keeling) Islands Territory, Rudist Seamount (11°03'47"S, 99°26'36"E), depth 3780–3839 m, 12/10/2022 (1 spec.); W.54420 (LK308), Cocos (Keeling) Islands Territory, Rudist Seamount (11°03'47"S, 99°26'36"E), depth 3780–3839 m, 12/10/2022 (1 spec.); W.54383 (LK304), Cocos (Keeling) Islands Territory, Muirfield Seamount (13°26'12"S, 96°18'17"E), depth 3948–4047 m, 24/10/2022 (1 spec.); W.54508 (LK314), Christmas Island Territory, Attention Seamount (11°45'25"S, 103°16'49"E), depth 1401–1408 m, 9/10/2022 (1 spec. not removed from tube). Description. Tube: white or slightly brownish opaque, jirkovi Kupriyanova, 1993c has elongate operculum and its with smooth surface, circular in cross-section, attached to collar’s ventral lobe has a deep medial incision, thus making substrate throughout its entire length ( Fig. 10A View Figure 10 ). the collar four-lobed. Hyalopomatus nogueirai n. sp. is most Radiolar crown: with up to 10 pairs of radioles ( Fig. 10B View Figure 10 ), similar to H. macintoshi (Gravier, 1911) from Antarctica and arranged pectinately, easily detachable from short radiolar H. mironovi from Kuril-Kamchatka Trench as both species lobes. Inter-radiolar membrane and stylodes absent. Terminal have globular transparent opercula, slightly flattened on top. filaments of radioles thin. Radiolar eyes and mouth palps However, both these species have tri-lobed collars, while not observed. in H. macintoshi tubes bear with well-developed flaring Peduncle: smooth, cylindrical, thin (approximately same peristomes. thickness as radioles) ( Fig. 10A View Figure 10 ); inserted outside radiolar The phylogenetic results also show that that H. cf. crown proper, between base of 1 st and 2 nd radioles. mironovi from North Fiji is nested inside the Hyalopomatus Collar and thoracic membranes: collar long, completely nogueirai n. sp. clade instead of forming a clade with H. covering radiolar lobes and distinctly unlobed ( Fig. 10B, I View Figure 10 ). mironovi from Kuril-Kamchatka Trench (the type locality). Collar continuous with short thoracic membranes ending at This suggests that the specimen attributed to H. mironovi by 2 nd chaetiger ( Fig. 10E View Figure 10 ). Kupriyanova et al. (2010) likely belongs to Hyalopomatus Operculum : soft membranous, semi-transparent, semi- nogueirai n. sp. globular, with flattened top, slightly differentiated from

Etymology. The species is named after Professor João basal part; conspicuous constriction and additional small

Miguel de Matos Nogueira (Universidade de São Paulo, vesicular ampulla between operculum and peduncle present

Brazil) for his important contributions to serpulid ( Fig. 10A View Figure 10 ). Pseudoperculum absent.

systematics. Thorax: with 6 chaetigerous segments, 5 of which uncinigerous ( Fig. 10I View Figure 10 ). Small bundle of collar chaetae (Fig. Distribution. Only known from seamounts off Christmas 10E) of two types: limbate and fin-and-blade with distal and Cocos (Keeling) Islands, Indian Ocean, 932–4047 m. blade separated from basal fin by a short gap ( Fig. 10C View Figure 10 ). Subsequent chaetae limbate, of two sizes, Apomatus chaetae absent ( Fig. 10D View Figure 10 ). Uncini along entire thorax rasp-shaped, Hyalopomatus rossanae n. sp. with 20–25 small teeth in profile view, with 6 teeth in row above flat anterior peg made of 3–4 rounded lobes (Fig. urn:lsid:zoobank.org:act:9675EECD-427B-4398-9C2C-1A123B8B9C6E 10H). Pair of prostomial eyes absent. Triangular depression Fig. 11A–J View Figure 11 absent, thoracic tori almost parallel to mid-lateral line of thorax ( Fig. 10B, I View Figure 10 ). Material examined. Holotype: W.54369 (LK289), Cocos Abdomen: with up to 55 segments. Chaetae long, nearly (Keeling) Islands Territory, Muirfield Seamount (13°26'12"S, capillary with only narrow geniculate tip made of two rows 96°18'17"E), depth 3948–4047 m, 24/10/2022. of pointed teeth ( Fig. 10G View Figure 10 ). Capillary chaetae present in Paratypes: W.53432 (LK260), Territory of Christmas posterior chaetigers ( Fig. 10F View Figure 10 ). Uncini rasp-shaped with over Island, Karma Seamount (12°49'33"S, 107°02'48"E), 20 teeth in profile and up to 8 rows of teeth ( Fig. 10J View Figure 10 ) above depth 2860– 2850 m, 11/07/2021 (1 spec.); W.53459 anterior peg flat divided into 3–5 rounded lobes (crenulated). (LK267), Territory of Christmas Island, Clara Marie Achaetous anterior abdominal zone present. Seamount (13°34'35"S, 105°19'39"E), depth 2189–2264 m, Size : total body length up to 11 mm, including up to 12/07/2021 (1 spec.); W.54374 (LK294), Cocos (Keeling) 5.9 mm long radioles, 1.2 mm long thorax, 4.2 mm long Islands Territory, Investigator Ridge Abyssal (11°15'26"S, abdomen, width of thorax 0.5 mm. External tube diameter 97°58'08"E), depth 4980–4990 m, 12/10/2022 (1 spec.); up to 0.6 mm, corresponding lumen diameter 0.5 mm. W.54378 (LK292), Cocos (Keeling) Islands Territory GoogleMaps

(12°13'32"S, 96°57'36"E), depth 1113–1343 m, 17/10/2022 Diagnostic remarks. Hyalopomatus nogueirai n. sp. has an (1 spec. prepared for SEM); W.54392 (LK276), Cocos operculum with a differentiated endcap flattened at the top (Keeling) Islands Territory, Muirfield Seamount (13°05'33"S, and a clearly unlobed collar. A distinct character of the new 96°21'09"E), depth 2889–2923 m, 23/10/2022 (1 spec.); species is the multilobed pegs of thoracic uncini because W.54394 (LK277), Cocos (Keeling) Islands Territory, other species of the genus tend to have two-lobed pegs of Investigator Ridge Abyssal (11°15'26"S, 97°58'08"E), depth such uncini. The multilobed pegs of thoracic uncini are also 4980–4990 m, 12/10/2022 (1 spec.); W.55292 (LK307), found in H. dieteri , the species that is distinct in having Cocos (Keeling) Islands Territory, Rudist Seamount thick-walled, quadrangular in cross-section tubes. However, (11°03'47"S, 99°26'36"E), depth 3780–3839 m, 12/10/2022 at least some two-lobed uncini in older literature may be due (1 spec.). to high power microscope observations, misinterpreting the real structure of the “gouged” peg. Description. Tube: white opaque, with shiny surface, The multilobed thoracic uncini formally separate the thin-walled, circular in cross-section, attached to substrate new species from other congeners having globular or pear- throughout entire length, no keels, peristomes or obvious shaped vesicular opercula without differentiated distal caps transverse ridges or growth lines ( Fig. 11C, D View Figure 11 ). ( H. claparedii Marenzeller, 1878 , H. langerhansi Ehlers, Radiolar crown: with 6–7 pairs of radioles, arranged 1887, and H. sombrerianus ( McIntosh, 1885)) . It is distinct pectinately, easily detachable from short radiolar lobes. Interfrom H. nigropileatus (Ehlers, 1900) having an elongate radiolar membrane and stylodes absent. Terminal filaments spindle-shaped operculum covered with dark violet or black of radioles thin, spirally twisted. Radiolar eyes and mouth distal cap with a net-like structure, and H. sikorskii having palps not observed. an operculum with distal dark cap flat on top resembling a Peduncle: smooth, cylindrical, approximately same brimless domed hat without net-like structure. Hyalopomatus thickness as normal radioles ( Fig. 11B View Figure 11 ), inserted outside radiolar crown, between base of 1 st and 2 nd radioles. Material examined. Holotype: W.54438 (LK278); Cocos Collar and thoracic membranes: collar long covering (Keeling) Islands Territory, Cocos (Keeling) (12°1'10"S, radiolar lobes, trilobed, with ventral lobe at least twice as 96°50'11"E), depth 754–890 m, 16/10/2022. Paratype: long as lateral ones ( Fig. 11B View Figure 11 ). Collar continuous with short W.54366 (LK285), same as above (1 spec. prepared for rounded thoracic membranes ending at 2 nd chaetiger (Fig. SEM).

11A, B).

Description. Tube: white opaque, with shiny surface, Operculum: soft membranous, semi-transparent,

straight, thin-walled, brittle, circular in cross-section, keels elongated with convex brown cap, distinctly differentiated

and peristomes absent, distinct breaks present ( Fig. 12A View Figure 12 ).

from basal part; conspicuous constriction and additional

Radiolar crown: with 7 pairs of radioles in holotype, small vesicular ampulla between operculum and peduncle

arranged pectinately, easily detachable from short radiolar ( Fig. 11B, C, E, e View Figure 11 ). Pseudoperculum absent.

lobes. Inter-radiolar membrane and stylodes absent. Terminal Thorax: with 6 chaetigerous segments, 5 of which

filaments of radioles thin, spirally twisted. Radiolar eyes and uncinigerous ( Fig. 11A, B View Figure 11 ). Small bundle of collar chaetae

mouth palps not observed.

of two types: simple limbate and fin-and-blade with distal

Peduncle: smooth, cylindrical, thin (approximately same blade separated from basal fin by a short gap ( Fig. 11F, J View Figure 11 ).

thickness as radioles) ( Fig. 12A, a View Figure 12 ).

Subsequent chaetae limbate, of two sizes, Apomatus chaetae

Collar and thoracic membranes: collar long, covering absent ( Fig. 11I View Figure 11 ). Uncini along entire thorax rasp-shaped,

radiolar lobes, trilobed, with ventral lobe distinctly higher with 20–25 small teeth in profile view, with 6–8 teeth in

than lateral ones. Collar continuous with short thoracic row above flat peg made of two rounded lobes ( Fig. 11G View Figure 11 ).

membranes ending at 3

rd chaetiger.

Pair of prostomial eyes absent. Triangular depression absent,

Operculum: soft membranous, semi-transparent, distinctly thoracic tori almost parallel to mid-lateral line of thorax.

globular, no distal cap; conspicuous constriction and Abdomen: with up to 40 segments. Abdominal chaetae

additional small vesicular ampulla between operculum and not observed, likely absent. Uncini rasp-shaped with over 20

peduncle absent ( Fig. 12A View Figure 12 ). Pseudoperculum absent.

teeth in profile and up to 9 rows of teeth ( Fig. 11H View Figure 11 ) above

Thorax: with 6 chaetigerous segments, 5 of which anterior peg flat divided into 3–4 rounded lobes (crenulated).

uncinigerous. Small bundle of collar chaetae, of two types: Achaetous anterior abdominal zone long.

limbate and fin-and-blade with distal blade separated from Size: total body length up to 7.0 mm, including up to

indistinct basal fin by a short gap ( Fig. 12B View Figure 12 ). Subsequent 3.0 mm long radioles, up to 1.0 mm long thorax, 3.0 mm

chaetae limbate, of two sizes, Apomatus chaetae absent (Fig. long abdomen, width of thorax up to 0.2 mm. External tube

12D). Uncini along entire thorax rasp-shaped, with 20–25 diameter in holotype 0.3 mm, corresponding lumen diameter

small teeth in profile view and 6–8 teeth in row above flat 0.25 mm.

anterior peg made of two rounded lobes ( Fig. 12C View Figure 12 ). Pair Diagnostic remarks. The tiny new species is most similar to of prostomial eyes absent. Triangular depression absent, Hyalopomatus nigropileatus , H. jirkovi Kupriyanova, 1993c , thoracic tori almost parallel to mid-lateral line of thorax.

and H. sikorskii Kupriyanova, 1993c by having an elongate Abdomen: with up to 35 segments. Chaetae long, nearly operculum covered with a darker distal cap. Hyalopomatus capillary with only narrow geniculate tip made of two rows rossanae n. sp. differs from H. nigropileatus that is distinct of pointed teeth ( Fig. 12F View Figure 12 ). Capillary chaetae present in in having dark violet or black cap with a net-like structure. posterior chaetigers. Uncini rasp-shaped with over 20 teeth in The new species differs from H. sikorskii (having operculum profile and up to 9 rows of teeth ( Fig. 12E View Figure 12 ) above anterior peg with a distal dark cap flat on top) by having a trilobed collar flat divided into 3–5 rounded lobes (crenulated). Achaetous with very long ventral lobe, whereas H. sikorskii has short anterior abdominal zone absent.

collar with lobes of equal length. Finally, although both Size: total body length up to 7.0 mm, including up to 1.4 Hyalopomatus rossanae n. sp. and H. jirkovi have the collar mm long radioles, 1.2 mm long thorax, 4.4 mm abdomen, with the ventral lobe much longer than the lateral ones, the width of thorax up to 0.3 mm. External tube diameter in ventral lobe of collar in H. jirkovi has a deep medial incision, holotype 0.4 mm, corresponding lumen diameter 0.35 mm. thus making the collar four-lobed.

Diagnostic remarks. The new species is characterised by The molecular results here supported monophyly of

its distinctly globular operculum lacking any differentiated the genus Hyalopomatus and placement of Hyalopomatus

distal cap and its straight tube with smooth shiny surface, rossanae n. sp. in this genus.

attached only by the posterior part to substrate. Other similar

Etymology. The species is named in honour Professor Hyalopomatus spp. having opercula without differentiated Rossana Sanfilippo (University of Catania, Italy), an expert distal caps are H. claparedii Marenzeller, 1878 from the on systematics and palaeoecology of Serpulidae and other Arctic Ocean and H. mironovi Kupriyanova, 1993c from tube-dwelling polychaetes. the Kuril-Kamchatka Trench in the North-West Pacific

Ocean. Hyalopomatus suelindsayae n. sp. having a globular

Distribution. Only known from seamounts off Christmas

operculum differs from H. claparedii and H. mironovi that and Cocos (Keeling) Islands, Indian Ocean, 1113–4990 m.

have pear-shaped opercula. Hyalopomatus mironovi also has tubes with slight transverse ridges and special collar chaetae Hyalopomatus suelindsayae n. sp. with The a distinct new species large fin also well appears separated to from be morphologically the distal blade. urn:lsid:zoobank.org:act:414F6723-28BD-4EA0-9989-C6C4F93128F5 different from the poorly known taxa H. sombrerianus and H.

langerhansi, both from West Atlantic Ocean. Hyalopomatus Fig. 12A–F View Figure 12 sombrerianus , originally described as Serpula sombreriana

McIntosh, 1885, was based on a single dry non-operculate specimen 12 mm long, dredged off Sombrero, St. Thomas, the Caribbean Sea, in 859– 713 m. The taxon was transferred to Hyalopomatus by ten Hove in Ben-Eliahu and Fiege (1996). The type examined by ten Hove proved to be a mutilated specimen with broken chaetae (fide Ben-Eliahu & Fiege, 1996). The status of this species is uncertain, both Ben-Eliahu and Fiege (1996) and ten Hove and Kupriyanova (2009) suggested that the species is probably includes H. langerhansi . The description of the latter species was based on two finds collected by the “ Blake ” expedition (1868), northwest of Cuba (near Havana in 535 m, and 23°42'N 83°19'W, in 1572 m) (fide Zibrowius, 1969). According to Hartman (1938), the type material is badly damaged. The specimens have tubes with a sub-quadrangular section in its attached part, having two slight keels, which is a potential diagnostic character. As in H. claparedii , the operculum of H. langerhansi is a transparent pear-shaped vesicle.

Molecular results of this study indicate that H. suelindsayae n. sp. from IOT is most closely related to an unnamed Hyalopomatus sp. 1 from the Jaco Summit hydrothermal seep on the Costa Rica margin and to H. mironovi collected from the Kuril-Kamchatka trench. The taxonomic status of Hyalopomatus spp. populations from these localities needs to be examined into further studies.

Etymology. The species was named to honour Sue Lindsay, formerly Australian Museum, now SEM laboratory manager at Macquarie University, Sydney for her invaluable help and support over years.

Distribution. Only known from Cocos (Keeling) Islands Territory, Indian Ocean, 754– 890 m.