Scolelepis Blainville, 1828

Genus: Scolelepis Blainville, 1828 View in CoL

Species: Scolelepis ( Scolelepis) capensis ( McIntosh, 1924)

Figs 4–9 View FIGURE 4

Nerine capensis McIntosh, 1924: 38 View in CoL . Nerine cirratulus var. capensis McIntosh, 1925: 71 , 72. Nerine cirratulus View in CoL (not Delle Chiaje, 1831) Day, 1955: 407, 412 (fig. 1 j). Scolelepis squamata View in CoL — Day, 1967: 483 (fig. 18.7 c–h); Day et al. 1970: 29; Millard & Broekhuysen 1970: 282; Day, 1974: 60

(fig. 47); McLachlan et al. 1981: 221 (fig. 3); Bally 1983: 89 ( Table 3); McLachlan 1985: 157, 158 (figs 2; 3); Bally 1987:

766 ( Table 2); Hodgson 1987: 156; Bursey & Wooldridge 2002: 236 ( Table 1); Harris et al. 2014: Supplementary Tables S1

& S 3; Appendix 4; Branch & Branch 2018: 90 (fig. 4.15); Branch et al. 2022: 70 (not fig. 27.4).

Type material: Neotype (here designated; SAMC-A089266 ): Southern Atlantic Ocean , South Africa, False Bay: Muizenberg Beach, 34°06'22.1"S, 18°28'35.8"E, eulittoral ( 0–0.3m depth), 13 March 2024, medium to fine sand, collected by L. V. Smith, C.A. Simon, and S. Schoeman, complete specimen, fixed and stored in>96% ethanol GoogleMaps . Topotypes: SAMC-A089267 and SAMC-A089268 ; collection data as for neotype GoogleMaps .

Material examined: Strand Beach, 34°06'58.0"S, 18°49'24.5"E, eulittoral ( 0–0.3m depth), 24 February 2024, medium to fine sand, collected by L. V. Smith, C.A. Simon, S. Schoeman, and Z. Nel, fixed in>96% ethanol. 20 specimens ( SAMC-A089269 to SAMC-A089273 ), 34°06'58.0"S, 18°49'24.5"E, eulittoral ( 0–0.3m depth), tissue removed for genetic sequencing after examination ( Table 4). Muizenberg Beach 34°06'22.1"S, 18°28'35.8"E, eulittoral ( 0–0.3m depth), 13 March 2024, medium to fine sand, collected by L. V. Smith, C.A. Simon, and S. Schoeman, fixed in>96% ethanol. Type material ( SAMC-A089266 – SAMC-A089268 ) and 5 whole specimens used for genetic sequencing after examining ( Table 4) GoogleMaps .

Iziko Museum of South Africa collection: SAM-MB-A020762 (3), Mouth of Sandvlei at Muizenberg, Western Cape, South Africa , 34°06'14.52"S, 18°28'30.48"E, 4 June 1947, unknown coll. SAM-MB-A021426 (1), Nahoon Estuary Flood-Tidal Delta, East London , Eastern Cape, South Africa , 32°58'56.95"S, 27°56'38.83"E, 11 November 1992, unknown coll. SAM-MB-A021427 (1), Nahoon Beach, East London , Eastern Cape, South Africa , 32°58'56.95"S, 27°56'38.83"E, 27 November 1992, unknown coll. SAM-MB-A060462 (5), Langebaan, Western Cape, South Africa , 33°5'28.92"S, 18°1'50.97"E, 6 December 1953, unknown coll GoogleMaps .

COI BOLD Barcode Index Number ( BIN): AGO5865.

Description: Neotype complete specimen, 109 chaetigers, 32.63 mm long and 1.2 mm wide at chaetiger 7. Other specimens had 68–109 chaetigers, 5.67–33.6 mm long and 0.175 –1.3375 mm wide at chaetiger 7.

Peristomium sharply tapered anteriorly as snout beyond prostomium ( Figs 4A–B View FIGURE 4 ; 5A), median suture present ( Figs 4B View FIGURE 4 ; 5A). Caruncle narrows to middle or end of chaetiger 2 ( Fig. 5A). Occipital antenna absent. Peristomium distinct from chaetiger 1 ( Fig. 5B). Two pairs of eyes, arranged in trapezoidal shape anterior to base of palps, anterior pair more elliptical or reniform, set further apart than posterior pair which are oval or round ( Fig. 4B View FIGURE 4 ). Eyes sometimes appear as a row with the outer pair being reniform and inner pair more rounded. Nuchal organ U-shaped ciliary bands beside caruncle posterior to base of palps ( Fig. 5A).

Palps extend posteriorly to chaetigers 12–27 ( 27 in neotype). Palp ciliation in two rows of longitudinal bands of transverse rows of short non-motile cilia; short rows on lateral side, 29–36 μm long and long rows on medial side, 36–58 μm in length; short rows more abundant than long rows ( Fig. 5C). Mucus-secreting cells in rows, with tubular necks ( Fig. 5D), mucus gland opening at the tip. Palp sheaths present, fused at base of palps with rugose surface ( Figs 4A View FIGURE 4 ; 5B).

Branchiae start from chaetiger 2 to end of body, dorsally tapered and best developed between chaetigers 4–10 (chaetiger 5 in neotype) ( Fig. 5B); ciliation along inner and outer edge ( Figs 6C View FIGURE 6 ; 7C View FIGURE 7 ); fewer cilia on outer edge between glandular tip of notopodial lamellae and subdistal portion of each branchia. Glandular tips without ciliation ( Figs 6A–C View FIGURE 6 ; 7C View FIGURE 7 ). Anterior notopodial lamellae fused to branchiae for most of their length, typically more than two-thirds to three-quarters, only glandular tips remaining free ( Figs 4A–B View FIGURE 4 ; 6A–C View FIGURE 6 ; 7C View FIGURE 7 ); clear distinction between branchiae and notopodial lamellae ( Fig. 7C View FIGURE 7 ). Middle and posterior notopodial lamellae fused to branchiae base, branchiae glandular tips and less than a quarter of the branchiae length free ( Fig. 6D View FIGURE 6 ).

Notochaetae of chaetiger 1 fine, elongate ( Fig. 5B), shorter and fewer than on succeeding chaetigers ( Fig. 6D View FIGURE 6 ). Notochaetal lamellae of chaetiger 1 ( Fig. 5B) rounded, shorter and positioned more dorsally than on succeeding chaetigers ( Fig. 6A, D View FIGURE 6 ). Neurochaetal lamellae of chaetiger 1 smaller and more rounded or oval-shaped than notochaetal lamellae; smaller, positioned more dorsally than succeeding neurochaetal lamellae. Neurochaetae fine and elongate, similar to notochaetae, but shorter and often fewer than succeeding neurochaetae ( Fig. 6B View FIGURE 6 ). Fine, primary transverse ciliated bands across dorsum of each chaetiger, continuous with ciliation along inner edge of branchiae ( Fig. 6C View FIGURE 6 ).

Anterior notopodial lamellae very elongated, narrow, fused to branchiae along most of their length, from chaetiger 2–3 to chaetiger 20–47; only blunt dorsal tips free ( Figs 5B; 6A View FIGURE 6 ; 7A–C View FIGURE 7 ). Outer margin of notopodial lamellae with slight notch in superior third or quarter, typically from chaetigers 3–45 (from chaetigers 2–33 in neotype) ( Figs 6A View FIGURE 6 ; 8A View FIGURE 8 ). In middle chaetigers (typically from 31–71), notopodial lamellae become more auricular in shape and notch becomes less prominent ( Figs 5E; 6A View FIGURE 6 ). In posterior chaetigers notopodial lamellae only attached to branchiae at mid to lower end of lamellae, top half free from branchiae; auricular in shape but smaller than in middle region ( Figs 6D View FIGURE 6 ; 7H View FIGURE 7 ).

Neuropodial lamellae on chaetiger 1 rounded or oval, increasing in size till fully developed at chaetiger 3 to 6 (chaetiger 4 in neotype) ( Figs 5B; 6A–B View FIGURE 6 ). From chaetigers 2–32 (chaetigers 2–31 in neotype) sub-rectangular with rounded edges ( Figs 5B; 6B View FIGURE 6 ). Distinct notch in neuropodial lobes start on chaetigers 17–33 ( Figs 6B View FIGURE 6 , 8A View FIGURE 8 ), eventually forming superior and inferior lobes, typically occurring around chaetigers 23–41 (chaetiger 36 in neotype) ( Fig. 6D View FIGURE 6 ). Superior lobe larger, auricular with blunt tip free, inferior lobe smaller, rounded, often stub-like ( Fig. 5F); similar shape in posterior region, but neuropodial lamellae lobes heavily reduced in size in last chaetigers ( Fig. 6D View FIGURE 6 ). Positive correlation found between total number of chaetigers and start of neuropodial lamellae notch ( Fig. 8A View FIGURE 8 : r = 0.58, R² = 0.34, p = 0.048), but no correlation with first occurrence of notopodial lamellae notch ( Fig. 8A View FIGURE 8 : r = -0.04, R² ≈ 0.00, p = 0.91). Lateral ciliated organs present between notopodial and neuropodial lamellae from chaetiger 1 to posteriormost chaetigers ( Fig. 5E).

Notopodial chaetae thin, elongate, 7–20 per ramus, unilimbate (sometimes bilimbate) ( Fig. 7A–D View FIGURE 7 ), slightly bent posteriorly. Middle chaetigers with 3–12 notochaetae, posterior chaetigers with 2–8 ( Fig. 7H View FIGURE 7 ) ( neotype has 12–19, 5–8, and 1–6 notochaetae in anterior, middle and posterior regions, respectively).

Neuropodial chaetae thin,elongate, unilimbate shafts and bent backwards( Fig.7E View FIGURE 7 ). Generally, 6–18 neurochaetae in anterior region ( Fig. 7B–C, E View FIGURE 7 ), 0–17 in middle and 0–6 (usually 0–2) in posterior ( Fig. 7F View FIGURE 7 ) (in neotype 15–18, 8– 14, and 1–6 neurochaetae in anterior, middle and posterior regions, respectively), more chaetae present in superior to inferior positions (often one in superior and none in inferior).

Neuropodial hooded hooks typically start on chaetigers 21 to 41 ( 38 in neotype) ( Fig. 8B View FIGURE 8 ), 1–15 hooks per fascicle ( 3–15 in neotype), 0–5 companion or alternating capillaries ( 0–5 in neotype) above the hooks in middle and posterior regions ( Figs 5F; 6D View FIGURE 6 ; 7F–G View FIGURE 7 ). Teeth of hooded hooks predominantly bluntly rounded and bidentate, <90° between main fang and apical tooth,> 90° between shaft and main fang ( Fig. 7F–G View FIGURE 7 ). Hook shafts tend to bend prominently downward ( Fig. 5F) and elongate in the posterior slightly more than in middle region but then shorten again in last few chaetigers.

Notopodial hooded hooks first appear on chaetigers 36–89 ( 89 in neotype) ( Fig. 8B View FIGURE 8 ). Usually 1–7 ( 2–7 in neotype) notopodial hooded hooks per row ( Fig. 7H View FIGURE 7 ), accompanied by 1–9 companion or alternating capillaries per fascicle ( 4–9 in neotype). More notopodial capillaries in superior position than inferior, generally 1–4 per fascicle (2–6 capillaries in superior position in neotype). Notopodial capillaries decreasing in number and size posteriorly. Strong correlations present between total number of chaetigers and first occurrence of both notopodial ( Fig. 8B View FIGURE 8 : r = 0.91, R 2 = 0.83, p <0.001) and neuropodial hooded hooks ( Fig. 8B View FIGURE 8 : r = 0.68, R 2 = 0.46, p = 0.016).

Pygidium disk-shaped, globular edges (rounded, cushion-like in neotype) ( Figs 4C View FIGURE 4 ; 5G).

Colouration: Colour in life opaque, light pink-red in anterior ( Fig. 4A–B View FIGURE 4 ), darker red-brown in posterior. Branchiae with visible red blood vessels, notopodial lamellae, prostomium and peristomium white ( Fig. 4A–B View FIGURE 4 ). Preserved colour off-white, cream in anterior, brown to dark-grey in posterior which lightens towards the end.

Methyl green staining pattern: Dark blue staining on both notopodial and neuropodial lamellae, and glandular tips ( Fig. 9B View FIGURE 9 ). Intense blue pigmentation of pygidium ( Fig. 9D, F View FIGURE 9 ). Anterior prostomium, peristomium, caruncle and palp sheaths with uniformly dispersed blue speckles ( Fig. 9A–C View FIGURE 9 ). Each chaetiger with two transverse ventral stripes on either side of midline; anterior stripe wider and more intensely stained ( Fig. 9C View FIGURE 9 ). Only one ventral transversal stripe on posterior chaetigers ( Fig. 9D View FIGURE 9 ).

Geographic distribution: Atlantic Ocean, South Africa: Muizenberg ( McIntosh 1924, 1925; Day 1967; Harris et al. 2014; this study), Strand (this study), Langebaan ( Day 1967). Indian Ocean, South Africa: Nahoon, East London (this study). Wider distribution from Northern Cape coastline through to northern KwaZulu Natal ( Harris et al., 2014) and possibly further north to Namibia ( McLachlan 1985), Mozambique and Madagascar ( Day 1967), but these records need to be confirmed.

Habitat and ecology: Scolelepis capensis inhabits the upper intertidal to shallow subtidal zones of sandy beaches and mouths of estuaries (e.g., Day 1955, 1967; Millard & Broekhuysen 1970; Hodgson 1987; Bursey & Wooldridge 2002), occupying sand grain tubes bound by mucus. Some individuals have parasitic ciliate epibionts, attached to the ends of posterior hooded hooks (present in neotype) ( Fig. 9E–G View FIGURE 9 ), resembling those described for Polydora neocaeca on the east coast of North America ( Williams & Radashevsky 1999). Similar associations between spionids and ciliates have been reported from the west coast of North America ( Douglass & Jones 1991) and the Mediterranean Sea (Bick 2002), suggesting that these associations are widespread among spionids (Makic et al. 2020). However, the majority of ciliate species reported from polychaete hosts worldwide remain undescribed.

Justification for neotype: The type material originally deposited at the Natural History Museum in London ( NHM) has been lost since it was examined by Day (Emma Sherlock, NHM, personal communication). To resolve this, fresh material collected from the type locality (Muizenberg) was compared with the descriptions by Day (1955, 1967) and the more recent account by Surugiu et al. (2022). Based on these comparisons, an amended description and new molecular sequence data for Scolelepis capensis are provided. In accordance with the International Code of Zoological Nomenclature ( ICZN 1999), a neotype is designated here to serve as an objective reference for the nominal taxon and to ensure nomenclatural stability. The neotype was collected from the type locality and, along with two topotypes, are deposited at the Iziko South African Museum.

Taxonomic remarks: Scolelepis capensis is morphologically similar to S. squamata and other species within the genus that were previously synonymised with S. squamata .

While the anterior notopodial lamellae of S. squamata and S. agilis are bilobed ( Surugiu et al. 2022; Bonavia et al. 2025), S. capensis has a single lobed notopodial lamella. The notopodial lobe in S. capensis is broader and shorter than in S. squamata and S. agilis and is distinctly more auricular. The degree of fusion between the branchiae and notopodial lamellae is also greater in S. capensis , with only about a quarter of the lamella length and glandular tips remaining free from the branchiae, compared to little more than half of the lamella length in S. squamata .

In most Scolelepis species, the neuropodial lamellae develop a central notch in the mid-body chaetigers, leading to a division into a larger superior lobe and a smaller inferior lobe. This division occurs between chaetigers 23– 41 in S. capensis , 20–38 in S. agilis ( Bonavia et al. 2025) , and 17–38 in S. squamata ( Surugiu et al. 2022) . In S. capensis , the superior lobe is auricular, while the inferior lobe is smaller, rounded, and often stub-like. The neuropodial lamella is rounded or oval on chaetiger 1 and sub-rectangular with rounded edges from chaetigers 2 to 32. Similarly, S. squamata initially has semi-oval neuropodial lamellae that enlarge, becoming sub-rectangular in shape with rounded margins ( Surugiu et al. 2022). The superior lobe gradually becomes elongated and narrow, while the inferior lobe reduces to a small, papilliform cirrus in the posterior chaetigers. In contrast, S. agilis has rounded neuropodial lamellae throughout that increase in size posteriorly, with a more distinct notch developing in the middle chaetigers ( Bonavia et al. 2025). The superior lobe remains larger than the inferior one but does not become notably elongated.

In the subgenus Scolelepis ( Scolelepis) Blainville, 1828 , neuropodial hooks appear first, followed by notopodial hooks in more posterior segments. Species differ according to arrangement and shape of hooded hooks. In S. capensis , neuropodial hooks first occur between chaetigers 21–41, ranging from 1–15 hooks per fascicle, bluntly rounded and bidentate throughout, similar to S. mesnili ( Surugiu et al. 2022) . S. agilis has fewer hooks appearing from chaetigers 27–34 (up to 12 per fascicle on posterior segments) and a rounded main fang ( Bonavia et al. 2025). S. squamata hooded hooks are initially bluntly rounded and bidentate but become unidentate in the posterior ( Surugiu et al 2022). Neuropodial hooks, numbering 4–10 per fascicle, first appear between chaetigers 23–46. Furthermore, shafts of hooded hooks curve prominently in S. capensis whereas hooded hook shafts are only gently bent in S. squamata .

Colouration in live specimens differ greatly: Scolelepis capensis shows pink-red and red-brown tones, while S. squamata displays dusky-greenish and dark grey shades ( Surugiu et al. 2022), and S. agilis exhibits translucent blues and greens ( Bonavia et al. 2025).