Laonice (Norgensia) costaricensis, Sikorski & Pavlova, 2018

Sikorski, Andrey & Pavlova, Lyudmila, 2018, Two new species of Laonice (Norgensia) (Spionidae, Polychaeta) from subtropical Atlantic and subequatorial Pacific coasts of North America, Zootaxa 4418 (2), pp. 171-178 : 173-175

Laonice (Norgensia) costaricensis sp. nov.

( Figure 2 )

Laonice cirrata Dean et al., 2012 : p. 366.

Holotype: Bahia Chatham (5.55°N 87.05°W), algae, 28 m, 7 Oct. 2007 ( MCZ 101143 ).

Paratypes: Bahia Chatham (5.55°N 87.05°W), algae, 28 m, 7 Oct. 2007 ( MCZ 141960 , 1 ) . Isla del Coco , Bahia Chatham, grab, 28 m, 7 Oct. 2007, collector J.A. Sibaja ( MZUCR 246-02 , 1 ) ; Isla del Coco , Bahia Chatham, trawl, 24 m, April 2008, collector J.A. Sibaja ( MZUCR 223-01 , 1 ) ; Isla del Coco , Bahia Chatham, grab, 65 m, April 2008, collector J.A. Sibaja ( MZUCR 348-05 , 1 ) .

Description. Holotype: Complete specimen 0.3 mm wide, 10 mm long for 66 chaetigers. Neuropodial hooded hooks appear from chaetiger 17, up to 5 per neuropodium. Nuchal organ extending to chaetiger 11. Chaetiger 45 is the last one carrying branchiae. Sabre chaetae present from chaetiger 11, one per fascicle. Genital pouches appear on chaetiger 12 (genital pouches absent after chaetiger 21).

All material examined: One paratype is a complete specimen 0.3 mm wide, 9 mm long for 63 chaetigers. Three paratypes are anterior fragments between 0.5 and 0.8 mm wide.

Prostomium blunt, anteriorly rounded, entire or very slightly indented, without frontal or lateral horns. Caruncle following nuchal organ extending to chaetiger 11–20. One pair of large eyes. Long, finger-like occipital antenna present on posterior part of prostomium, behind eyes. Peristomium not fused to prostomium ( Fig. 2A ). No palps remain. Branchiae present from chaetiger 2 on about ¾ of the following chaetigers. Branchiae free, separate from notopodial lamellae throughout; longest on anterior third of specimen, first branchiae approximately the same length as notopodial lobe ( Fig. 2C ), by about chaetiger 7 approximately twice the length of notopodial lobe ( Fig. 2D ), and in posterior half up to four times the length of the lobes ( Fig. 2E–F ). Notopodial postchaetal lobes reduced to small subtriangular projection on chaetiger 1; then leaf-like and slightly pointed until about chaetiger 7 ( Fig. 2C–D ), thereafter becoming more rounded and gradually reduced to small round lobes ( Fig. 2E–F ). Neuropodial postchaetal lobes leaf-like from chaetiger 1; ventrally rounded and dorsally pointed until about chaetiger 6 ( Fig. 2C ), becoming gradually rounded and reduced in size after about chaetiger 15 ( Fig. 2E–F ). Transversal dorsal membranes not pronounced—only on the largest specimen low membranes between branchiae present. Genital pouches from chaetiger 10–17. Anterior capillaries in two rows only on one paratype ( MZUCR 246-02), all other specimens have capillaries arranged in three rows from chaetiger 5 to 10–11. Neuropodial hooded hooks appear from chaetiger 15–20, 5–7 per fascicle, bi- or tridentate (with two paired apical teeth above the main fang arranged side by side) ( Fig. 2G–H ). Neuropodial sabre chaetae first present on chaetiger 9–12, 1–2 per fascicle.

The only pygidium remaining in the material belongs to the holotype; it has two large ventral lobes but no dorsal cirri exist or remain ( Figs 2B ).

Methyl green. No special staining pattern detected.

Distribution. Isla del Coco, Bahia Chatham, 24– 65 m.

Etymology. Name is given after the name of the country Costa Rica.

Remarks. This species is morphologically close to L. lemniscata give authority, described from Southwest Australia. The latter species was described on a basis of 5 specimens, of a similar size to the type specimens of L. costaricensis sp. nov.

However, according to the original description L. lemniscata does not have anterior capillaries arranged in more than two vertical rows. Nevertheless, communication with Dr Robin Wilson (Senior curator of the marine invertebrate collection in Museum Victoria, Melbourne, Australia) allowed us to partially clarify the original diagnosis of L. lemniscata . Wilson found that in the largest specimen (holotype) of L. lemniscata the notochaetae of chaetigers 3–8 and the neurochaetae on chaetigers 6–8 were arranged in three rows. He allowed the possibility that this is an example of size variability; however almost all smaller specimens of L. costaricensis sp. nov. have the anterior capillaries arranged in 3 rows. Moreover, the presence of transdorsal crests is clearly mentioned in the original description of L. lemniscata , whereas specimens of L. costaricensis sp. nov. have no pronounced transdorsal crests. The absence of well-pronounced transdorsal crests is the main distinguishing feature from other species in this subgenus. Paired apical teeth above the main fang in hooded hooks of L. costaricensis is also the character distinguishing it from L. lemniscata .

Figures

FIGURE 2. Laonice (Norgensia) costaricensis sp. nov. A. Anterior end, dorsal view; B. Posterior end with pygidium, ventral view; C–F. Parapodia of chaetigers 2, 7, 24 and 42; G–H. Hooded hook from chaetiger 42, side and frontal view. A–B—Holotype (MCZ 101143); C–G—Paratype (MZUCR 348-05).Scale:A–B, D–F—0.5 mm; C—0.3 mm; G—0.05 mm.