Terebellides congolana, Parapar & Martin & Moreira, 2020

Parapar, Julio, Martin, Daniel & Moreira, Juan, 2020, On the diversity of Terebellides (Annelida, Trichobranchidae) in West Africa, seven new species and the redescription of T. africana Augener, 1918 stat. prom., Zootaxa 4771 (1), pp. 1-61 : 18-23

Terebellides congolana sp. nov.

Figures 11A , 12A , 13−15 , 37 ; Tables 1, 2 urn:lsid:zoobank.org:act:F56164BC-1B78-4ECE-ACA5-543E5D75EB90

Material examined. Type material. Four specimens: holotype ( MNCN 16.01 /18582); three paratypes ( MNCN 16.01 /18581, 16.01/18583 and 16.01/18584, Table 1) .

Diagnosis. Body large (31–33 mm in length), with branchial anterior lobe, posterior ventral lobes much smaller than dorsal ones, with short terminal filament, and emerging after fusion line of dorsal ones. TC1 notopodia and notochaetae much longer than following ones. Thoracic neurochaetae with rostrum / capitium length about 1/1, and capitium with a first row of 4–5 big teeth followed by a second row of much smaller, progressively smaller teeth.

Description based on holotype

Measurements and general body features. Complete specimen, 31.0 mm long and 3.0 mm wide ( Fig. 12A ); female with oocytes in body cavity. Body tapering posteriorly, with segments increasingly shorter and crowded towards pygidium. Prostomium compact; large tentacular membrane surrounding mouth with typical buccal tentacles with expanded tips ( Fig. 13A, E ). SGI as an expanded structure below tentacular membrane ( Fig. 13 A–B). Lateral lappets on SGIII–VIII (TC1–6), larger in SGIII–VII (TC1−5) ( Fig. 13 A−E). Low oval-shaped glandular region in CH 3 in some specimens ( Fig. 13B ), but not evident.

Branchiae. Branchiae arising as single structure from SGIII, with a single short-stalked mid-dorsal branch ( Fig. 12A , 13 A−B, E), one pair of long dorsal (upper) lobes 50% fused, reaching TC6−7 ( Fig. 13C ) and one pair of ven- tral (lower) lobes about 1/5 as long as dorsal ones), not fused together and arising from mid-length of dorsal lobes fusion line ( Fig. 13 A−B). Anterior projection of dorsal lobes (lobe 5) large, about 1/4 length of posterior dorsal lobes ( Fig. 13E ). Pointed projection of posterior region only in lower lobes, as a short and thick terminal filament ( Fig. 13A ). Both sides of branchial lamellae with several parallel bent rows of cilia and ciliated papillae on outer edge ( Fig. 14 C−D).

Thorax. Eighteen pairs of notopodia (SGIII−XX), with dorsal ciliated papillae ( Fig. 14 E−F). TC1 much more developed and with longer notochaetae than subsequent ones ( Fig. 13B, E ). All notochaetae as simple capillaries. Neuropodia as sessile pinnules from TC6 (SGVIII) to body end, with uncini in single rows starting from TC7 (SGIX) throughout. First neuropodia (TC6) with four sharply bent, acute tipped, geniculate chaetae ( Fig. 15B ) having minute teeth forming an ill-defined capitium. From TC7, neuropodia with 8−14 uncini per torus in one row, with long-shafted denticulate hooks, rostrum about same length as capitium, with 4−5 big teeth above main fang surmounted by several much smaller denticles ( Fig. 15 C−E).

Abdomen. About 40% of body length, with 31 pairs of neuropodia as erect pinnules ( Fig. 15G ); about 25–30 uncini per torus having four teeth above main fang surmounted by 3–4 teeth in irregular middle row and an upper crest of several smaller teeth ( Fig. 15H ).

Other body features. One well-developed nephridial papilla behind each TC1 notopodium ( Fig. 14E ), and two pairs of nephridial openings in TC4 and TC5 ( Fig. 14F ). Pygidium blunt, funnel-like depression.

Methyl green staining pattern. Anterior CH 1 to CH 9 solid; CH 10 to CH 18 striped; being CH 10 to CH 11 much more marked than following; J-shaped glandular region marked lateral to CH 3; near pattern 5 of Schüller & Hutchings (2010) ( Fig. 37 ).

Variability. Body between 31 and 33 mm in length. Type locality. Off Congo (Table 1). Distribution and bathymetry. Off Congo; sandy mud; 47−167 m depth ( Fig. 11A ; Table 1). Etymology. The name of the species refers to the type location, the Republic of Congo. Remarks. Terebellides anguicomus Müller, 1858 sensu Solís-Weiss et al. (1991) resembles T. congolana sp. nov. in having large sized-branchiae reaching TC6 but differs in having a large transverse dorsal hump on TC5 and 17 thoracic chaetigers (18 in T. congolana sp. nov. and most species of the genus, see key below).

Terebellides congolana sp. nov. also differs from other African species in having posterior ventral branchial lobes that are much smaller and located distally, but the following ones also have this character: T. rigel Schüller & Hutchings, 2013 ; T. mediterranea Parapar, Mikac & Fiege, 2013 ; T. akares Hutchings, Nogueira & Carrerette, 2015 , T. persiae and T. hutchingsae . However, T. rigel is a deep-water species (> 2000 m) from the Weddell Sea and does not bear long TC1 notopodia and notochaetae; T. akares was described from coral reefs (Lizard Island, NE Australia) and has a distinctly short abdomen; T. persiae is a shallow-water species from the Iranian coast, that has a much more developed anterior branchial lobe and a distinct dorsal hump at TC6; T. hutchingsae is also a shallow subtidal species from the Gulf of Thailand, that bears geniculate chaetae in two chaetigers, TC5 and TC6, instead of only one in TC6. The closest species to T. congolana sp. nov. is T. mediterranea , a shallow-water species (31 m depth) from the Adriatic Sea; it also bears branchiae with a similar shape and very small ventral posterior lobes arising near the distal end of the branchiae, and TC1 notopodia and notochaetae longer than following, but it differs from the new species in having a shorter body (21 mm in length vs. 31 mm in T. congolana sp. nov.) and a much larger tentacular membrane.

Terebellides europaea Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 , from the French coast of the Bay of Biscay, also shares with T. congolana sp. nov. the long notopodia and notochaetae of TC1, but it differs from the new species in having papillar projections over the edge on anterior branchial lamellae, much bigger ventral branchial lobes and attached to the branchial stem, and in lacking ciliated papillae in branchial lamellae.

Figures

FIGURE 11. Maps of Central and Southern Atlantic African coasts showing the stations where the species of Terebellides described in this work were found. (A) T. africana stat. prom., T. augeneri sp. nov. and T. congolana sp. nov.; (B) T. fauveli sp. nov. and T. kirkegaardi sp. nov.; (C) T. longiseta sp. nov. and T. nkossa sp. nov.; (D) Terebellides sp. 1, Terebellides sp. 2 and T. ramili sp. nov.

FIGURE 12. Terebellides congolana sp. nov. (holotype, MNCN 16.01/18582): (A) anterior end, left lateral view and detail of branchiae. Terebellides fauveli sp. nov. (holotype, NHMD-636920): (B) anterior end, right lateral view and detail of branchiae. Abbreviations: bdltp—branchial dorsal lobe terminal papilla; bldl—branchial left dorsal lobe; blvl—branchial left ventral lobe; brdl—branchial right dorsal lobe; brvl—branchial right ventral lobe; bvltf—branchial ventral lobe terminal filament; loli—low- er lip; TC—thoracic chaetiger; tnc—thoracic notopodial chaetae.

FIGURE 13. Terebellides congolana sp. nov. Stereomicroscope images of anterior end of holotype (B, MNCN 16.01/18582) and two paratypes (A, C–E, MNCN 16.01/18581 and 16.01/18583). (A) right latero-ventral view and detail of branchia ventral lobes; (B) left lateral view and detail of TC1 notochaetae; (C) dorsal view; (D–E) left lateral view. Abbreviations: abl—anterior branchial lobe; bdlfl—branchial dorsal lobes—fusion line; bldl—branchial left dorsal lobe; bdltp—branchial dorsal lobe terminal papilla; blvl—branchial left ventral lobe; brdl—branchial right dorsal lobe; brvl—branchial right ventral lobe; bvltp—branchial ventral lobe terminal papilla; dh—dorsal hump; latlap—lateral lappet; loli—lower lip; no—nephridial opening; SG—segment; TC—thoracic chaetiger; tc1not—thoracic chaetiger 1 notopodium; tc3gr—thoracic chaetiger 3 glandular region; tnc—thoracic notopodial chaetae; TU—thoracic unciniger.

FIGURE 14. Terebellides congolana sp. nov. SEM micrographs of the paratype MNCN 16.01/18584. (A) anterior end, left lateral view; (B) anterior branchial lobe, detail; (C–D) branchial lamellae ciliature, detail; (E) TC1–TC2, lateral view, framed in (A); (F) TC4–TC5, lateral view, framed in (A). Abbreviations: abl—anterior branchial lobe; bcp—branchial ciliated papilla; brdl—branchial right dorsal lobe; cr—ciliary row; no—nephridial opening; np—nephridial papilla; TC—thoracic chaetiger; tndp—thoracic notopodium dorsal papilla; SG—segment.

FIGURE 15. Terebellides congolana sp. nov. SEM micrographs of the paratype MNCN 16.01/18584. (A) thoracic notopodium; (B) TC6 geniculate chaetae; (C–E) thoracic uncini, upper view; (F) thorax-abdomen transition area, ventral view; (G) two abdominal neuropodia, ventro-lateral view; (H) two abdominal uncini, frontal view.

FIGURE 37. Body staining patterns—following Schüller & Hutchings (2010)—in ventral view of the species described in this work; chaetigers indicated in Arabic numbers.