Leocrates giardi Gravier, 1900

Leocrates giardi Gravier, 1900 View in CoL

Figs. 6–8 View FIGURE 6 View FIGURE 7 View FIGURE 8

Leocrates giardi Gravier 1900: 180–185 View in CoL , text-figs. 46–52, pl. 10, figs. 17–19 [original description; Gulf of Aden]. — Salazar-Vallejo 2020: 55 View Cited Treatment , figs. 29, 30 [redescription based on type material and additional material from the Gulf of Suez and Red Sea coast of Saudi Arabia].

Leocrates claparedii View in CoL . — Fauvel 1919: 371 [erroneous assignment of the Red Sea material to the Mediterranean L. claparedii View in CoL ; Gulf of Aden, Red Sea, Arabian-Persian Gulf]. — Fauvel 1933: 44–45 [erroneous assignment of the Red Sea material to the Mediterranean L. claparedii View in CoL ; Gulf of Suez, Red Sea] [ non L. claparedii View in CoL (Costa in Claparède 1868)].

Leocrates diplognathus View in CoL . — Fauvel 1955: 105 [erroneous record from the Red Sea] [ non Paralamprophaea diplognatha ( Monro 1926)].

Material examined. 1 specimen, FLMNH UF 12511 , Saudi Arabia, Makkah Governate, Thuwal, KAUST, King Abdullah Monument , 22.340608°N 39.087519°E, shallow sandflat near mangrove, depth 0.2–0.5 m at low tide, suction pump, in burrow, leg. A. Anker et al., 21.06.2022 [fcn AA-22-080] GoogleMaps ; 1 specimen, FLMNH UF 12512 , same collection data as for previous specimen [fcn AA-22-068] GoogleMaps ; 1 specimen, FLMNH UF 12513 , Saudi Arabia, Makkah Governate, Thuwal, KAUST, King Abdullah Monument , 22.340608°N 39.087519°E, shallow reef flat with some seagrass and coral rubble, depth 0.5–1 m, suction pump, in burrow, leg. A. Anker, 24 September 2022 [fcn AA-22-229] GoogleMaps ; 1 specimen, FLMNH UF 12514 , Saudi Arabia, Makkah Governate, Thuwal, KAUST, King Abdullah Monument , 22.340608°N 39.087519°E, sandflat close to mangroves, depth 0.3–0.5 m at low tide, suction pump, in echiuran burrow near mangrove roots, in burrow, leg. A. Anker, V. Semin, G. Kolbasova, 1 March 2025 [fcn KSA_42868] GoogleMaps ; 1 specimen, FLMNH UF 12515 , Saudi Arabia, Makkah Governate, Thuwal, KAUST, King Abdullah Monument , 22.340608°N 39.087519°E, sandflat adjacent to mangroves, depth 0.3–0.5 m at low tide, suction pump, in echiuran burrow, leg. V. Semin and G. Kolbasova, 28 March 2025 [fcn KSA_42979]. GoogleMaps All specimens complete. Pharynx everted in 3 specimens.

Description (based on all examined material). Body wide anteriorly; slightly tapering posteriorly, with 16 chaetigers ( Fig. 6 View FIGURE 6 ). Body length 15–26 mm, maximum width without parapodia 1.5–2.5 mm, with parapodia 3– 5 mm. Prostomium slightly longer than wide, wider anteriorly in specimens with everted pharynx, with almost parallel lateral margins in specimens with retracted pharynx; lateral margins straight ( Fig. 7A–B View FIGURE 7 ). Lateral antennae about 1.5 times longer than prostomium, slightly longer than palps, with short ceratophores. Palps with palpophores about 3 times longer than palpostyles. Median antenna inserted between posterior eyes, tapering, not reaching anterior margin of prostomium. Eyes brownish; each anterior eye 1/10 or slightly less of prostomial width, oval or round, sometimes emarginate, slightly larger than rounded posterior eyes; distance between anterior eyes slightly exceeding distance between those of posterior pair (greater in specimens with everted pharynx). Nuchal organs horizontal, C-shaped, dorsally visible lobes, their posterior portions sometimes obscured by tentacular belt; ciliated bands barely visible dorsally.

Facial tubercle variable in shape ( Fig. 7A, B View FIGURE 7 ), globular, ovoid, tapering or almost equilaterally triangular, possibly depending on extent of pharynx eversion and/or fixation. Lateral vesicles of pharynx (seen in 1 specimen) equal, with tapering anterior portion ( Fig. 7A View FIGURE 7 ). Both pharyngeal rings and ventral side of peristomial ring with longitudinal ribs separated by shallow grooves ( Fig. 7 View FIGURE 7 ). Ventral side of peristomium with each rib subdivided into 2 secondary ribs; anterior margin edged with low papillose ridge ( Fig. 7D View FIGURE 7 ). Anterior margin of pharynx with 10–15 low marginal papillae at each side; number of papillae both in papillose ridge and anterior margin of pharynx dependent on specimen size. Jaws single, semi-transparent yellowish to brownish, tapering, pointed ( Fig. 7C, D View FIGURE 7 ). Upper jaw about twice as large as lower jaw and inserted ahead of latter.

Tentacular cirri long, thin, annulated. Cirrophores basally fused, with dark aciculae. Longest dorsal tentacular cirri posteriorly reaching chaetiger 6 to 8. Longest ventral tentacular cirri reaching chaetiger 2 or 3. Lateral cushions low, entire; longitudinal striae visible in all or only posterior segments in different specimens.

Chaetigers 1–4 with neurochaetae only. Notochaetae present from chaetiger 5 to last chaetiger. Notopodial acicular lobes elongate, tapering, with stout digitiform tips ( Fig. 8A View FIGURE 8 ). Notochaetae simple capillaries with fine denticles present subdistally, around 10 to over 20 per bundle towards mid-body. Major notoaciculum black, not entering tip of lobe. Minor aciculum slender, black with semitransparent basal part, situated below major aciculum ( Fig. 8A View FIGURE 8 ). Dorsal parapodial cirri long, thin, annulated ( Fig. 8A View FIGURE 8 ), reaching 6 or 7 chaetigers backwards in anterior and mid-body segments, generally shorter in posterior segments, in latter case as long as 2–5 adjoining chaetigers.

Neuropodial acicular lobes bluntly conical, longer than wide. Neurochaetae around 20 per bundle in mid-body (less in 1 st and posterior chaetigers), all heterogomph falcigers ( Fig. 8A View FIGURE 8 ). Blades bidentate, coarsely serrated at base ( Fig. 8B, C View FIGURE 8 ), with finer serrations continuing along cutting edge and gradually fading away; guards approaching subdistal tooth ( Fig. 8B, C View FIGURE 8 ) in most chaetae, reduced in inferior falcigers ( Fig. 8D View FIGURE 8 ). Blade length decreasing towards ventral side ( Fig. 8B–D View FIGURE 8 ): blades of superior falcigers 10–15 times as long as wide, those of inferior falcigers around 5–7 times as long as wide. Both neuroaciculae black. Major neuroaciculum not entering tip of acicular lobe. Minor aciculum relatively stout, lying above major aciculum, reaching to almost half parapodial length. Ventral parapodial cirri smooth, surpassing neurochaetal lobe by about half of their length ( Fig. 8A View FIGURE 8 ).

Pygidium with terminal anus; anal cirri as long as 5 to 9 posterior chaetigers.

Colour: Body reddish, somewhat translucent, with iridescent cuticle when alive ( Fig. 6A, B View FIGURE 6 ), beige after fixation ( Fig. 7 View FIGURE 7 ); prostomium opaque, crimson red ( Fig. 6C View FIGURE 6 ).

Distribution. North-western Indian Ocean: Red Sea, Gulf of Aden, Arabian-Persian Gulf ( Gravier 1900; Salazar-Vallejo 2020 and references therein; present study).

Ecology. All herein examined specimens were extracted from burrows in sand or muddy sand, sometimes with a coral rubble component, at depths not exceeding 1 m at low tide; two specimens were collected with thalassematid echiurans, Listriolobus sp. / Ochetostoma sp.

Remarks. Leocrates giardi was described by Gravier (1900) based on material from the Gulf of Aden ( Yemen and Djibouti), not the Red Sea, as somewhat confusingly stated by Salazar-Vallejo (2020): “Red Sea, Gulf of Aden”. The present specimens agree well with the type material of Gravier (1900) and the material redescribed by Salazar-Vallejo (2020), including from the Red Sea. Results of the phylogenetic analysis of Leocrates are discussed below. Noteworthy, in all our specimens, the blades and joints of falcigers are overgrown with threads of microalgae/ bacteria ( Fig. 8B View FIGURE 8 ).