Laonice galatheae, Sikorski, Andrey & Pavlova, Lyudmila, 2016

Sikorski, Andrey & Pavlova, Lyudmila, 2016, Three new species of Laonice (Polychaete: Spionidae) from West and Southwest Africa, Zootaxa 4097 (3), pp. 353-368 : 354-356

Laonice galatheae sp. nov.

( Figures 1 A–F, 2, 5)

Laonice cirrata — Kirkegaard 1959: 18 (partim).

Holotype: "Galathea"—Exp., off Angola, Loanda-Lobito, St. 116, 12°14.3ʼS, 13°27ʼE, 100 m, 20 Dec. 1950 (ZMUC-POL-643).

Paratypes: R/V "Atlantide"—Exp., Off Gold Coast, St. 75, 04°44ʼN, 01°36ʼW, 46 m, muddy sand, 23 Jan. 1946 (2 specimens, ZMUC-POL-639); R/V "Galathea"—Eksp., Guinea Bay, off River Congo, St. 75, 05°41ʼS, 11°38ʼE, 201 m, rather coarse mud, t=13,5°C, 0 7 Dec. 1950 (1, ZMUC-POL-640); "Galathea"—Eksp., Guinea Bay, off River Congo, St. 88, 06°24ʼS, 12°01ʼE, 75 m, 0 8 Dec. 1950 (1, ZMUC-POL-641); "Galathea"—Eksp., off Cunene river, St. 132, 17°13ʼS, 11°27ʼE, 200 m, 22 Dec. 1950 (1, ZMUC-POL-644).

Description. Holotype: anterior fragment with 33 chaetigers, 1.37 mm wide. Neuropodial hooded hooks appear from chaetiger 23, up to 4 per neuropodium. Nuchal organ extending to chaetiger 16. Last chaetiger carrying branchiae is not detectable. Sabre chaetae present from chaetiger 14, up to 4 per fascicle. Genital pouches appear on chaetiger 7 on the left side, 5 on the right (genital pouches absent after chaetiger 12 on the left side and after 13 on the right).

All material examined: from 1.20 to 2.25 mm wide at chaetigers 7–12 (only one specimen—ZMUC-POL- 640—was wider than 2 mm).

Prostomium almost triangular ( Figs 1 A, B; 2). Anterior margin of prostomium slightly rounded, not fused with peristomium at anterior corners. One pair of small eyespots (if visible—Fig. 1A) in the posterior part of prostomium. Occipital tentacle well developed, erect. It is possible to trace the length of nuchal organ in only three specimens (ZMUC-POL-640, 641 and 643): in two former cases, it reaches up to chaetiger 12 but in the last one it is possible to trace it until chaetiger 15. Caruncle does not seem to follow nuchal organ, it stops on the level of chaetiger 2. Short palps (extending to chaetiger 4 or 5) were intact only on one specimen (ZMUC-POL-640). Anterior 15–17 chaetigers slightly wider than the subsequent segments. Branchiae at chaetiger 2 are comparable in height to notopodial postchaetal lamellae, clearly lower than notopodial postchaetal lamellae at chaetiger 3, becoming obviously higher only from chaetiger 5. Branchiae present until chaetiger 33 in one specimen (Holotype); other specimens do not have intact branchiae on posterior segments. Last segment bearing branchiae not detected. Notopodial postchaetal lamellae of anterior 14 to 15 chaetigers with pointed tips ( Fig. 1 C). Notopodial postchaetal lamellae are not pointed in subsequent segments, but have a narrow and elongated upper part ( Fig. 1 D—arrow). Condition of the material does not allow description of the shape of notopodial lamellae in post branchial region. Prechaetal notopodial lamellae (in upper part of notopodia) large and most prominent from chaetiger 6 to 15 ( Fig. 1 C—arrows). Neuropodial postchaetal lamellae of anterior 3–4 chaetigers with acute lateral tips; lamellae rounded with small but recognizable acute peaks on the lateral margins on subsequent segments until chaetiger 16; upper margins of neuropodial lamellae are acute until chaetiger 25 or 26 and sharply pointed upward on the subsequent segments ( Fig. 1 D). Dorsal transverse membranes connecting bases of notopodial postchaetal lamellae were not detected. Genital pouches first appearing on chaetiger 5 or 6, continuing to chaetigers 9–16.

Number of segments bearing pouches from 4 to 10. Noto- and neuropodial capillaries arranged in more than two vertical rows per fascicle on anterior 17–19 chaetigers (in up to four rows between chaetigers 4–6 and 13–14). Neuropodial hooded hooks first appear from chaetiger 23 to 30, up to 6 per fascicle; hooks are bidentate in side view or tridentate ( Fig. 1 E–F) with apical teeth located in tandem; details are hardly visible without immersion. Sabre chaetae from chaetiger 13 to 18; 3–4 per fascicle at first appearance, reduced to only one after two to four segments. Notopodial hooks not found. Pygidium unknown.

Worms without pigment.

Methyl green staining pattern. The most stable patterns from 75% ethanol staining persists as ventral longitudinal stripes on the prostomium and on notopodial postchaetal lobes of chaetigers 2 till 9.

Distribution. West Africa, from Angola to Ivory Coast ( Fig. 5 ).

Etymology. The name is given after the name of the Danish expedition ship that collected most of the specimens of this species.

Remarks. Unfortunately, preservation of the material is quite poor and does not allow seeing well some morphological characters. This species is close to the group of species having capillaries arranged in more than 2 rows in anterior parapodia: L. appelloefi Söderström, 1920 ; L. weddelia Hartman, 1978 ; L. blakei Sikorski & Jirkov, 1988 ; L. nuchala Blake, 1996 ; L. norgensis Sikorski, 2003 ; L. maciolekae Aguirrezabalaga & Ceberio, 2005 and L. vieitezi Lopez, 2011 . L. maciolekae was synonymized (Meißner et al. 2014) with L. appelloefi . L. appelloefi , just as L. galatheae , has anterior notopodial prechaetal lobes, genital pouches from chaetiger 5–7, similar length of nuchal organ and similar shape of neuropodial hooks. But L. appelloefi has pointed notopodial postchaetal lobes only until chaetiger 7 or 8 whereas L. galatheae until chaetiger 14 or 15, and the obvious anterior widening of the body in L. appelloefi is absent in L. galatheae . L. weddelia and L. galatheae differ obviously in the length of the nuchal organ (to chaetiger 20 in L. weddelia and to chaetiger 12–15 in L. galatheae ) and by number of branchiae (to chaetiger 50 in L. weddelia and to chaetiger 33 in L. galatheae ). L. blakei differs from L. galatheae by multidentate hooks, by much longer branchiae on chaetiger 2 and by appearance of genital pouches from chaetiger 3. L. nuchala has about 20 segments bearing genital pouches (compared to 4–10 in L. galatheae ) starting from chaetiger 7–8 (compared to chaetiger 5–6 in L. galatheae ). L. norgensis and L. vieitezi differ from L. galatheae by more posterior appearance of genital pouches, by high transversal dorsal membranes on middle segments, by branchiae existing until nearly the very posterior chaetigers, and by longer nuchal organ.

Figures

FIGURE 1. Laonice galatheae sp. nov.: A – B. Anterior end, dorsal view; C. Parapodium, chaetiger 7 (arrows pointing to prechaetal notopodial lamellae); D. Parapodium, chaetiger 27 (arrows pointing to a narrow and elongated upper part of notopodial postchaetal lamella); E. Hooded hook in side view, chaetiger 29; F. Hooded hook in three-quarter view, chaetiger 33. Material: A, D – E. Holotype (ZMUC-POL- 643); B. Paratype (ZMUC-POL- 639); C. Paratype (ZMUC-POL- 641), F. Paratype (ZMUC-POL- 641). Scales (mm): A, C, D— 1; B— 2; E, F— 0,03.

FIGURE 5. Distribution of the new species along the African coast: filled circles— Laonice galatheae sp. nov.; square— Laonice cricketae sp. nov.; triangle— Laonice olgae sp. nov.