Lepidonopsis barnichae, Salazar-Silva, Patricia & Carrera-Parra, Luis Fernando, 2014

Salazar-Silva, Patricia & Carrera-Parra, Luis Fernando, 2014, Revision of Lepidonopsis humilis (Augener, 1922) and description of L. barnichae sp. nov. (Annelida: Polychaeta: Polynoidae) based upon morphological and molecular characters, Zootaxa 3790 (4), pp. 555-566 : 562-565

Lepidonopsis barnichae sp. nov.

Figures 4–6

Lepidonopsis humilis .— Pettibone 1977: 50 –54, figures 5a–f (partim); Gómez et al. 1997: 1070 (non Augener, 1922). Lepidonotus sp. 3. — Salazar-Silva 2006: 154, 156.

Material examined. Type material: Holotype ECOSUR0164, Acapulco, Guerrero, Mexico, Angosta beach, 16°50'30.90" N, 99°54'54.33" W, in oyster Spondylus calcifer , 4 March. 2009, coll. S.I. Salazar-Vallejo & L.F. Carrera-Parra. Paratypes ECOSUR0165, Acapulco, Guerrero, Hornos beach, 16°51'6.4″ N 99°54′ 1″ W, in sponge, coll. S.I. Salazar-Vallejo & L.F. Carrera-Parra, 20 Apr. 2008, 1 spm. ECOSUR0166, Acapulco, Guerrero, Hornos beach, 16°51′6.4″ N 99°54′.1″ W, in oyster Spondylus calcifer , 19 Apr. 2008, coll. S.I. Salazar-Vallejo & L.F. Carrera-Parra, 1 spm. ECOSUR0167 Acapulco, Guerrero, Hornos beach, 16°51′ 6.4" N 99°54′ 1″, in oyster Spondylus calcifer , 19 Apr. 2008, coll. S.I. Salazar-Vallejo & L.F. Carrera-Parra, 1 spm.

Additional material examined. Guerrero, Acapulco: Cantiles, La Quebrada, coll. A. Medina, in oyster, 26 May. 2000, 8 m, ECOSUR-P2670, 2 spm. Cantiles, Quebrada, Coll. A. Medina, in oyster 25 May. 2000, 15 m, ECOSUR-P2671, 2 spm. La Condesa, coll. Salazar-Vallejo, in oyster, 27 Nov. 1999, ECOSUR-P2672, 2 spm. Oaxaca: La Entrega, Coll. L. Mitchell, 0 1 Aug. 1986, ECOSUR-P1383, 1 spm.

Diagnosis. Segment 2 dorsally projected over the prostomium as a single small lobe ( Fig. 4 B). Elytra with conical macrotubercles ( Fig. 5 B, E, F), tuft of papillae on dorsal surface isolated from the principal fringe of papillae ( Fig. 5 A, C–D), first three pairs of elytra with macrotubercles larger and slightly curved ( Fig. 5 B–F) than in remaining elytra; neurochaetae with bidentate tip.

Description. Holotype ECOSUR0164, mature female, complete with 26 segments. Body of uniform width, length 7 mm, width 2 mm.

Prostomium bilobed, wider than long, without prostomial peaks. Median antenna brown, inserted frontally, with cylindrical ceratophore, style missing; two lateral antennae, inserted terminally, fused to distal end of prostomium as prolongations of prostomial lobes, without ceratophores or styles. Two pairs of dark eyes, anterior pair larger than posterior, inserted dorsolaterally at widest part of prostomium; posterior pair near posterior margin of prostomium. Palps smooth with dark brown pigmentation ( Fig. 4 A–B). Pharynx not everted. Tentacular segment not visible dorsally. Tentaculophores inserted lateral to prostomium, with slender chaetae. Tentacular cirri missing. Segment two projected dorsally over prostomium as a small lobe ( Fig. 4 B); parapodia directed forward; ventral oral cirri longer than following.

Elytra 12 pairs, on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23; last three segments with dorsal cirri. Elytra covering dorsum completely; overlapping medially and posteriorly ( Fig. 4 A); brown spots over surface except elytrophore area, darker on anterior elytra. All elytra with fringe of marginal papillae, tuft of papillae on dorsal surface isolated from fringe ( Fig. 5 A, C–D). First pair of elytra rounded, almost circular ( Fig. 5 A); surface with sclerotized macrotubercles and microtubercles, abundant digitiform micropapillae around each macrotubercle. Macrotubercles conical with tips slightly curved, wide areoles at base, largest over elytrophore area ( Fig. 5 B); microtubercles conical with wide areole. Second and third pair of elytra reniform ( Fig. 5 C), posterior elytra oval ( Fig. 5 D). Dorsal surface with digitiform papillae, macrotubercles and microtubercles sclerotized; macrotubercles subconical, shorter than on second and third pair of elytra, distally blunt ( Fig. 5 E); microtubercles similar to macrotubercles, flattened where elytra overlap.

Parapodia biramous ( Fig. 4 C). Notopodia smaller than neuropodia, with short acicular lobe. Neuropodia with prechaetal lobe slightly projecting, postchaetal lobe shorter; distally rounded with abundant filiform papillae. Dorsal cirri with cirrophore basally expanded, with digitiform papillae distally; style tapering to filiform tip, without papillae, brown pigmentation at base ( Fig. 4 C). Elytrophores wider than dorsal tubercles. Ventral cirri tapering to filiform tip. Notochaetae slender, surface with rows of spines, tapering to capillary tip. Neurochaetae with two or three rows of spines on upper region, tips bidentate, main tooth thick, subdistal tooth smaller ( Fig. 4 D).

Nephridial papillae present from segment 6, larger on median and posterior segments, also elongated on ovigerous specimens. Anus dorsal, pygidium with papillae on margin, anal cirri missing. Oocytes 50–150 Μm in diameter, present from segment 11, including the parapodia.

Variation. Specimens examined varied in length from 4 to 13 mm, and in width from 1 to 3 mm. In some specimens the antennae, palps, and venter have dark brown pigmentation, in others it is lighter and diffuse. In some specimens the macrotubercles on the first pair of elytra are truncated cones ( Fig. 5 F), in other specimens, they are conical with tips curved.

Barcode. Nucleotide sequences between 653-661 bp of the section of COI gene used for barcoding were obtained from the holotype and paratypes. The average evolutionary divergence over the four sequence pairs was 1%.

Discussion. Lepidonopsis barnichae sp. nov. resembles L. humilis by having bidentate neurochaetae and smooth palps, while L. collinifer has unidentate neurochaetae and minutely papillated palps. L. barnichae sp. nov. differs from the other two Lepidonopsis species by having segment 2 dorsally projected over the prostomium as a single small lobe, whereas L. humilis has two lobes on segment 2, and L. collinifer lacks these projections. L. barnichae sp. nov. has conical and slightly curved macrotubercles, while these are hemispherical and covered by small nodules in L. humilis and conical in L. collinifer . Furthermore, all elytra of L. barnichae sp. nov. have an abundant tuft of short or long papillae on the dorsal surface, isolated from the principal fringe of papillae ( Fig. 5 A, C–D). In L. humilis the tuft is present only on the first pair of elytra, while in L. collinifer this tuft of papillae is absent.

The morphological differentiation between L. barnichae sp. nov. and L. humilis was supported by the barcoding data which showed a genetic divergence of 17.5% ( Fig. 6 ). Previous studies have concluded that sequence divergences among closely related species of polychaetes vary between 8.4% to 12.9% ( Jones et al. 2008; Vrijenhoek et al. 2009; Tovar-Hernández & Carrera-Parra 2011; Carrera-Parra & Salazar-Vallejo 2011; Yáñez- Rivera & Carrera-Parra 2012).

Etymology. This species is named in honor of Dr. Ruth Barnich, in recognition of her many contributions on the taxonomy of Polynoidae .

Type locality. Acapulco, Guerrero, Mexico.

Distribution. Mexican Pacific from Acapulco to Oaxaca.

Figures

FIGURE 4. Lepidonopsis barnichae sp. nov. Paratype ECOSUR 0165. A, complete, dorsal view; B, anterior end, dorsal view, arrow shows lobe of segment two; C, parapodium from median segment; D, neurochaeta. Scale: A, 1.5 mm; B, 0.3 mm, C, 0.2 mm, D, 212 µm.

FIGURE 5. Lepidonopsis barnichae. sp. nov. Holotype ECOSUR 0164 A, first elytron; B, macrotubercles, first elytron; C, second elytron; D, elytron from median segment; E, macrotubercles, second elytron. Paratype ECOSUR 0165 F, macrotubercles, first elytron. Scale: A, 0.15 mm; B, 45 µm; C – D, 0.25 mm; E, 42 µm; F, 20 µm.

FIGURE 6. Neighbor-joining tree of COI sequences of Lepidonopsis species using K 2 P distance.