Terebellides augeneri, 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 : 13-18

Terebellides augeneri sp. nov.

Figures 2B , 8−10 , 11A , 37 ; Tables 1, 2

urn:lsid:zoobank.org:act:147575A6-3605-4327-A3AD-F5F1C80A3D0D

Material examined. Type material. Six specimens: holotype ( MNCN 16.01 /18579); five paratypes ( MNCN 16.01 /18577, 16.01/18580, 16.01/1858 and NHMD-636919, Table 1) .

Diagnosis. Small/medium-sized species (7–19 mm in length). Branchial anterior lobe absent; posterior ventral lobes thinner than dorsal ones, with terminal projections, directly emerging from branchial stem. TC1 notopodia and notochaetae as long as following. Thoracic neurochaetae with rostrum / capitium length about 1/1, and capitium with a first row of 5–6 medium sized teeth followed by progressively smaller teeth.

Description based on holotype

Measurements and general body features. Complete specimen, 19 mm long and 1.5 mm wide; female with oocytes in body cavity ( Fig. 2B ). Body tapering posteriorly with segments increasingly shorter and crowded towards pygidium. Prostomium compact; large tentacular membrane surrounding mouth, with typical buccal tentacles and expanded tips ( Fig. 8C , 9A ). SGI as an expanded structure below tentacular membrane. Lateral lappets on SGIII– VII (TC1–5), larger in SGIV–VI (TC2–4) ( Fig. 2B , 8 C–D, 9A).

Branchiae. Branchiae arising as single structure from SGIII, with a single stalked mid-dorsal branch, one pair of dorsal (upper) not-fused lobes, and a pair of shorter ventral (lower) lobes, neither fused to each other, nor to dorsal ones, with short terminal projections ( Fig. 9C ). Anterior projection of dorsal lobes (lobe 5) absent ( Fig. 2B ). Both sides of branchial lamellae having several parallel rows of cilia and low ciliated tufts on lamellar outer edge ( Fig. 9 B−C).

Thorax. Eighteen pairs of notopodia (SGIII−XX), those of TC1 about as long as following ones. All notochae- tae as simple capillaries. Neuropodia as sessile pinnules from TC6 (SGVIII) to body end, with uncini in single rows, from TC7 (SGIX) throughout. First neuropodia on TC6, with 4–5 sharply bent, acute tipped, geniculate chaetae with minute teeth forming a well-defined capitium ( Fig. 10 C−D). From TC7, neuropodia with up to 5–10 uncini per torus in one row, with long shafted denticulate hooks, rostrum about same length as capitium, with 5−6 medium-sized teeth above main fang, and surmounted by two rows of progressively shorter teeth ( Fig. 10 A−B).

Abdomen. Thirty-one pairs of neuropodia, as erect pinnules with about 20−25 uncini per torus, with four teeth above main fang surmounted by an upper crest of similar sized teeth ( Fig. 10 E−F) and several smaller teeth above.

Other body features. Nephridial (?) papilla behind TC1; nephridial openings dorsal to any anterior thoracic notopodium not seen. Pygidium blunt, as a funnel-like depression.

Methyl green staining pattern. Anterior CH 1 to CH 4 solid; CH 5 to CH 11 striped; near pattern 1 of Schüller & Hutchings (2010) ( Fig. 37 ).

Variability. Body ranging from 7.0 to 19.0 mm in length.

Type locality. Off Angola; 73 m depth (Table 1) .

Distribution and bathymetry. Off Angola; 72−83 m depth ( Fig. 11A ; Table 1).

Etymology. This species is named after the German scientist and prolific marine zoologist Hermann Augener (1872–1938), as an homage to his numerous contributions to polychaete taxonomy.

Remarks. The branchiae of T. augeneri sp. nov. resemble those of T. hutchingsae Parapar, Moreira & Martin, 2016 in bearing ventral lobes much less developed than the dorsal ones and arising from the base of the latter, but differ in having wider and longer lobes and in lacking a longer terminal projection. Both species also differ in the size of the ciliature in branchial lamellae outer edge (much lower in T. augeneri sp. nov.), in the shape of thoracic uncini (with teeth surmounting the rostrum much bigger in T. augeneri sp. nov.) and in bearing geniculate chaetae in CH 5 and CH 6 (only in CH 6 in T. augeneri sp. nov.).

Terebellides ceneresi Lavesque, Hutchings, Daffe, Nygren & Londoño-Mesa, 2019 has in common with T. augeneri sp. nov. the general branchial shape, with very similar branchial lobes and ciliary tufts on both sides of the outer edge of lamellae and no papillar projections pointing over their edge. Nevertheless, both species differ in the thoracic uncini, both in the shape of main fang (straight in T. augeneri sp. nov.; terminally bent in T. ceneresi ) and the denticulation of capitium (5–6 teeth in first row in T. augeneri sp. nov.; 3–4 in T. ceneresi ).

Terebellides shetlandica Parapar, Moreira & O’Reilly, 2016 also bears ventral branchial lobes not fused to dorsal ones and arising directly from the branchial stem. However, it is much smaller than T. augeneri sp. nov. (up to 15 mm; Parapar et al., 2016c), the four posterior lobes are of similar size, and the branchial lamellae do not bear ciliated papillae.

In African Atlantic waters T. augeneri sp. nov. most closely resembles T. ramili sp. nov. (see below). However, it inhabits much deeper bottoms and is unique among African species because in the thoracic uncini all teeth surmounting the rostrum are very small and of the same size; in all other species, the first-row teeth are always larger than those of posterior rows.

Figures

FIGURE 2. Terebellides africana Augener, 1918 stat. prom. (lectotype, ZMH V1709): (A) anterior end, left lateral view and detail of branchiae. Terebellides augeneri sp. nov. (holotype, MNCN 16.01/18579): (B) anterior end, left lateral view and detail of branchiae. Abbreviations: bldl—branchial left dorsal lobe; blvl—branchial left ventral lobe; brdl—branchial right dorsal lobe; bt—buccal tentacle; TC—thoracic chaetiger.

FIGURE 8. Terebellides augeneri sp. nov. Stereomicroscope images of holotype (MNCN 16.01/18579) (A–C) and paratype (NHMD-636919) (D–E). (A) full specimen, ventral view; (B) anterior end, dorsal view; (C) anterior end, ventral view; (D) anterior end, ventral view; (E) anterior end, dorsal view. Abbreviations: bldl—branchial left dorsal lobe; blvl—branchial left ventral lobe; brdl—branchial right dorsal lobe; brvl—branchial right ventral lobe; bst—branchial stalk; latlap—lateral lappet; SG—segment; TC—thoracic chaetiger.

FIGURE 9. Terebellides augeneri sp. nov. SEM micrographs of the paratype MNCN 16.01/18578. (A) anterior end, left laterodorsal view; (B) left posterior-dorsal branchial lobe ciliation (framed in A); (C) the same in posterior end (framed in A). Abbreviations: bct—branchial ciliated tuft; bdltp—branchial dorsal lobe terminal papilla; bt—buccal tentacle; latlap—lateral lappet; no—nephridial opening; TC—thoracic chaetiger; TU—thoracic unciniger.

FIGURE 10. Terebellides augeneri sp. nov. SEM micrographs of the paratype MNCN 16.01/18578. (A) row of thoracic uncini, upper view; (B) two thoracic uncini, upper-lateral view; (C) TC6 geniculate chaeta, upper view; (D) the same, capitium, detail (framed in C); (E) abdominal uncini, upper view; (F) abdominal uncini, frontal view. Circles in (B) and (E) showing number of teeth on capitium. Abbreviations: cap—capitium; ros—rostrum.

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