Seepicola viridiplumi Rice, Tovar-Hernández, Ellison & Young, 2025

Seepicola viridiplumi Rice, Tovar-Hernández, Ellison & Young sp. nov.

Materials

Type status: Holotype. Occurrence: occurrenceID: 9F20A7F4-BA4E-5B6A-B41E-DFB18FD5D47E; Record Level: type: PhysicalObject; collectionID: BHSa 144; institutionCode: CNAP – ICML, UNAM; ownerInstitutionCode: POH- 72-001; basisOfRecord: PreservedSpecimen; dynamicProperties: Cruise Code = TN 391, Date of Collection = 14 June 2021, Latitude = 27.78237117, Longitude = - 91.50830855, Depth = 562 m, Notes = epibiotic on Acesta oophaga

Type status: Paratype. Occurrence: occurrenceID: 3A8CBE5B-263B-5D5B-AFC7-A7BA2EB395E3; Record Level: type: PhysicalObject; collectionID: BPSa 115; institutionCode: CNAP – ICML, UNAM; ownerInstitutionCode: POP- 72-003; basisOfRecord: PreservedSpecimen; dynamicProperties: Cruise Code = AT 50-04, Date of Collection = 16 October 2022, Latitude = 27.723677, Longitude = - 91.279372, Depth = 651 m, Notes = epibiotic on Acesta oophaga

Type status: Paratype. Occurrence: occurrenceID: AB4A10DA-E875-5DD1-BF99-6023F33E97E8; Record Level: type: PhysicalObject; collectionID: BHSa 167; institutionCode: CNAP – ICML, UNAM; ownerInstitutionCode: POP- 72-004; basisOfRecord: PreservedSpecimen; dynamicProperties: Cruise Code = TN 391, Date of Collection = 14 June 2021, Latitude = 27.78237117, Longitude = - 91.50830855, Depth = 562 m, Notes = epibiotic on Acesta oophaga

Type status: Paratype. Occurrence: occurrenceID: 46A27349-00EC-53A0-8824-CDC03618D18D; Record Level: type: Physical Object; collectionID: BPSa 92; institutionCode: UANL; ownerInstitutionCode: UANL- 8188; basisOfRecord: PreservedSpecimen; dynamicProperties: Cruise Code = AT 50-04, Date of Collection = 16 October 2022, Latitude = 27.723677, Longitude = - 91.279372, Depth = 651 m, Notes = epibiotic on Acesta oophaga

Type status: Paratype. Occurrence: occurrenceID: D8989B89-32DD-5A42-82F1-CAF2907013C2; Record Level: collectionID: BHSa 127; institutionCode: UNAL; ownerInstitutionCode: UANL- 8189; basisOfRecord: PreservedSpecimen; dynamicProperties: Cruise Code = AT 50-04, Date of Collection = 15 October 2022, Latitude = 27.723677, Longitude = - 91.279372, Depth = 562 m, Notes = free-living in authigenic carbonate

Type status: Paratype. Occurrence: occurrenceID: D7E69433-518E-5E1B-9CC5-82277F14B884; Record Level: type: PhysicalObject; collectionID: BPSa 88; institutionCode: CNAP – ICML, UNAM; ownerInstitutionCode: MEB-POP- 72-0058; basisOfRecord: SEM Stub; dynamicProperties: Stub Numbers = 1 - 3, Cruise Code = AT 50-04, Date of Collection = 16 OCtober 2022, Latitude = 27.723677, Longitude = - 91.279372, Depth = 651, Notes = epibiotic on Acesta oophaga

Type status: Paratype. Occurrence: occurrenceID: CD767440-FF78-5D67-AD62-33E69A9830C9; Record Level: type: PhysicalObject; collectionID: BPSa 123; institutionCode: CNAP – ICML, UNAM; ownerInstitutionCode: MEB-POP- 72-0058; basisOfRecord: SEM Stub; dynamicProperties: Stub Numbers = 4 & 5, Cruise Code = AT 50-04, Date of Collection = 16 October 2022, Latitude = 27.723677, Longitude = - 91.279372, Depth = 651 m, Notes = epibiotic on Acesta oophaga

Description

Tubes composed of fine sand and distal end tightly curled (Fig. 1 View Figure 1 D). Branchial crown light green (Fig. 1 View Figure 1 ) and trunk cream to red-brown colour in live worms. Preserved specimens with dark to pale cream-coloured trunk and branchial crown whitish. Branchial crown length 7.2 mm (4-7.5 mm) with 12 pairs of radioles (same for paratypes). Trunk length 39 mm (28-32 mm), 2.5 mm wide (1.4-2 mm). Fifteen thoracic (13-18) and 121 abdominal chaetigers (97-143).

Branchial crown is mostly symmetrical (Fig. 3 View Figure 3 B) with 2-3 ventral-most radioles with long, filiform tips as long as the space of 12 pinnules (Fig. 4 View Figure 4 A). Ventral-most radioles 1 / 8 the length of dorsal radioles. Branchial lobes short, as long as the peristomium collar segment (Fig. 2 View Figure 2 A-C). Mid-dorsal radiole lobe basal flanges narrow, entire and translucent (Fig. 2 View Figure 2 C and E; Fig. 4 View Figure 4 A). Ventral radiole lobe flanges short, broad, with rounded margin, transluscent (Fig. 2 View Figure 2 D, Fig. 3 View Figure 3 D and Fig. 4 View Figure 4 A). Radiolar flanges and palmate membrane absent (Fig. 2 View Figure 2 D). Pinnules long, uniform along radioles. Radiolar eyes absent. All radioles of holotype, except ventral most, with short, broadly truncate distal ends (Fig. 4 View Figure 4 B). Inner longitudinal margins of radioles with truncate tips have thick, brownish tissue (Fig. 4 View Figure 4 C-H); this tissue broadest near radiole tips, giving appearance of radiolar eyes, but lacking ommatidia (Fig. 4 View Figure 4 D-G). Some paratypes with mixed radiolar tips (long-filiform, short buttom-like). Radiolar skeleton with four rows of cells in lateral view (Fig. 4 View Figure 4 E and H). Crown of paratype 1 (BPSa 115) regenerating: shorter in comparison to holotype and other paratypes; pinnules rudimentary.

Anterior peristomial ring slightly exposed dorso-laterally between dorsal pockets and lateral collar margin (Fig. 2 View Figure 2 E; Fig. 7 View Figure 7 A). Posterior peristomial ring collar with mid-dorsal margins fused to faecal groove (Fig. 2 View Figure 2 E; Fig. 7 View Figure 7 A); dorsal collar margins form two low, rounded lappets (Fig. 2 View Figure 2 A and C). Dorso-lateral collar margins entire, forming " V " (Fig. 2 View Figure 2 A, C and E). Ventral lappets triangular with rounded distal margins mid-ventrally incised (Fig. 2 View Figure 2 D; Fig. 3 View Figure 3 A and Fig. 7 View Figure 7 A). Peristomial eyes present in paratypes 1 (BPSa 115) and 2 (BHSa 167). Dorsal lips triangular, erect, dorsal pinnular and radiolar appendages present (Fig. 3 View Figure 3 A, C-D and F); ventral lips short and rounded, ventral sacs absent. Peristomial chamers oval, low, translucent with internal dark brownish tissue placed between ventral lappets and parallel lamellae.

Chaetiger 1: (Fig. 6 View Figure 6 A-C, Fig. 7 View Figure 7 A, C), superior row long, narrowly-hooded notochaetae (Fig. 6 View Figure 6 A, B and Fig. 7 View Figure 7 C), inferior row one-half as long as superior with hoods slightly broader (Fig. 6 View Figure 6 C, Fig. 7 View Figure 7 C). Ventral shield rectangular, slightly divided transversally and longer than subsequent thoracic shields (Fig. 3 View Figure 3 A). Chaetigers 2-16 (2-13, 2-15, 2-16 or 2-18) rectangular ventral shields divided transversally in two equal parts; tori do not contact ventral shields (separated by reduced space) (Fig. 2 View Figure 2 B; Fig. 3 View Figure 3 A). Subsequent thoracic notochaetae in superior and inferior groups (Fig. 5 View Figure 5 C, Fig. 8 View Figure 8 A): superior row elongate, narrowly hooded; inferior group paleate, arranged in two rows with pointed mucro (Fig. 5 View Figure 5 D, Fig. 8 View Figure 8 A-C). Neurochaetae with companion chaetae and avicular uncini (Fig. 5 View Figure 5 A, B, Fig. 8 View Figure 8 E, F). Avicular uncini with several rows of small, similar-sized teeth above main fang (covering proximal half of main fang) (Fig. 8 View Figure 8 D), breast well developed, main fang with high crest and handles 2.5 times longer than main fang (Fig. 5 View Figure 5 E, F). Companion chaetae with symmetrical membranes teardrop-shaped (Fig. 5 View Figure 5 B, E, Fig. 8 View Figure 8 E, F) with long handles (Fig. 5 View Figure 5 A, E).

Abdominal segments with elongate, broadly-hooded neurochaete (Fig. 6 View Figure 6 A-D, Fig. 9 View Figure 9 A), with basal, broad knee (Fig. 6 View Figure 6 E, Fig. 9 View Figure 9 F). Neurochaetae in last quarter of body two times longer than in anterior abdominal segments (Fig. 9 View Figure 9 B). Notopodial uncini avicular with several rows of teeth above main fang, extending over 3 / 4 of main fang (Fig. 9 View Figure 9 C, E-G). Breast well defined, handles very short, shorter than length of main fang (Fig. 6 View Figure 6 F-H). Pygidium rounded, eyes absent (Fig. 3 View Figure 3 E). Gametes not observed.

Etymology

The specific epithet refers to the color of the radiolar crown in living specimens, from the Latin viridi meaning ' green'.

Taxon discussion

Several morphological observations led to the specimens being placed in a monotypic genus, rather than in Pseudopotamilla or Perkinsiana . The specimens have dorsal and ventral branchial lobe flanges as in Pseudopotamilla . However, specimens lack compound radiolar eyes and asymmetrical radiolar crown in Pseudopotamilla species (Table 2 View Table 2 ). On the other hand, members of Potamilla Malmgren 1866 , lack radiolar eyes ( Knight-Jones 1983, Fitzhugh 1989). Members of Seepicola viridiplumi gen. nov., sp. nov. cannot be placed in Potamilla because the former have dorsal lips with radiolar appendages and lack a palmate membrane, whereas Potamilla have dorsal lips without radiolar appendages, but a palmate membrane is present, amongst other differences (Table 2 View Table 2 ).

Fitzhugh (1989) emphasised that Perkinsiana Knight-Jones 1983 , is not defined by any synapomorphies to indicate monophyly. Capa (2007) and Tovar-Hernández et al. (2012) both described new species of Perkinsiana and remarked on the existing problem of properly assigning species to this genus. In the same context, Pseudopotamilla is not defined by any synapomorphies ( Fitzhugh 1989; Capa 2007) and, if not monophyletic, this could have distinct implications for recognising Eudistylia Bush, 1905 and Schizobranchia Bush, 1905 , as the clade ( Pseudopotamilla ( Eudistylia , Schizobranchia )) is defined by the presence of branchial lobe flanges and compound radiolar eyes. In both Pseudopotamilla and Perkinsiana , species are known to burrow in hard limestone, dead coral, barnacles and mollusc shells ( Chughtai and Knight-Jones 1988, Knight-Jones et al. 2017, Capa et al. 2019, Tovar-Hernández et al. 2020). There are 18 valid Perkinsiana species and 23 Pseudopotamilla species, according to Tovar-Hernández et al. (2020).

Members of S. viridiplumi gen. nov., sp. nov. lack a palmate membrane and radiolar flanges present in some Perkinsiana species. Additionally, members of S. viridiplumi gen. nov., sp. nov. have abdominal uncini with reduced handles, whereas these structures are short to medium length in Perkinsiana . Three types of abdominal chaetae can be present Perkinsiana species, whereas these are elongate, broadly hooded in all chaetigers of S. viridiplumi gen. nov., sp. nov.

Furthermore, the new species have distinctive features not previously described: the peculiar shape of radiolar tips, presence of the brown tissue on radioles and presence of a pair of peristomial chambers between the internal wall of the ventral lappets and parallel lamellae. Other features of the chaetae and uncini are typical of Pseudopotamilla . As with the new species, some species of Pseudopotamilla also have tubes that curl tightly at the end ( Knight-Jones et al. 2017), but branched or bifurcated tubes, which is an indication of asexual reproduction, were not seen. However, the variable number of thoracic chaetigers observed in S. viridiplumi gen. nov., sp. nov. might be indicative of asexual reproduction ( Kolbasova et al. 2013, Capa and Murray 2016).