Nipponnemertes incainca, Gonzalez-Cueto, Jaime, Castro, Lyda R. & Quiroga, Sigmer, 2017

Gonzalez-Cueto, Jaime, Castro, Lyda R. & Quiroga, Sigmer, 2017, Nipponnemertesincainca sp. n. Adoption of the new taxonomic proposal for nemerteans (Nemertea, Cratenemertidae), ZooKeys 693, pp. 1-15 : 1-3

Nipponnemertes incainca sp. n. Fig. 1 A–F

Material examined.

Holotype: COLOMBIA Santa Marta, Rodadero Inca-Inca beach (11°12'30.2"N, 74°13'54.5"W), intertidal zone under boulders, whole specimen in 70% ethanol (CBUMAG:NEM: 0056). Total body length 18.5 mm, 1 mm wide.

Paratypes: COLOMBIA Santa Marta, Taganga (11°15'51.23"N, 74°11'31.54"W), intertidal zone under boulders covered by sponges, whole specimen in 70% ethanol (CBUMAG:NEM: 0043). Total body length 11.7 mm, 1.8 mm wide.

COLOMBIA Santa Marta, Rodadero Inca-Inca beach (11°12'30.2"N, 74°13'54.5"W), intertidal zone under boulders, transverse histological sections of the proboscis; rest of specimen in 70% ethanol (CBUMAG:NEM:0049). Total body length 22.5 mm, 2.05 mm wide.

COLOMBIA Santa Marta, Rodadero Inca-Inca beach (11°12'30.2"N, 74°13'54.5"W), intertidal zone under boulders; tissue in absolute ethanol (CBUMAG:NEM:00068, CBUMAG:NEM:00069).

An entire additional worm, collected in Inca-Inca beach (11°12'30.2"N, 74°13'54.5"W) was used for DNA extraction. Sequence data for 615 bp of Cytochrome C Oxidase Subunit I deposited in GenBank under accession number KX879856 (see alignments with other congeners in supplemental information).

Etymology.

The specific epithet refers to the "Inca-Inca beach" site from which most of the specimens were collected; this name is in apposition.

Diagnosis.

Nipponnemertes incainca sp. n., like other members of Nipponnemertes , has a mid-dorsal cephalic ridge, is capable of retracting the head into the body when disturbed, and is capable of swimming. However, in this new species the anterior furrows and their secondary transverse grooves are faintly visible both macro- and microscopically and they are not visible in a ventral view.

Description.

Relaxed length from 11.7 mm to 22.5 mm and width 1 to 2 mm. Dorsal side uniformly bright red color (Fig. 1A). Ventral side lighter than dorsal side (Fig. 1). Head shield-shaped, slightly demarcated from rest of body but without V-shape cephalic groove and not wider than trunk. Mid-dorsal cephalic ridge present in head (Fig. 1A, 2A). Frontal organ with small cirrus. Cerebral organ furrows pre-cerebral, inconspicuous, with few faint ridges orthogonal to furrow axis. Brain distinguishable as a pale brown bilobed structure through dorsal and ventral body wall. Two irregular groups of eyespots situated at lateral margins in precerebral cephalic region (Fig. 2A), extending beyond brain parallel to lateral nerve cords. Rhynchopore subterminal. Proboscis long and stout, with papillae (Fig. 3B), pink in color when everted (Fig. 1B). Stylet (length: 87.4 µm) smooth, supported on an oval basis (54 × 38.3 µm); two pouches containing 3-4 accessory stylets each (Fig. 2B). Twelve proboscidial nerves present (Fig. 3 A–B). This species was found among sponges and brown algae underneath rocks, and in the crust formed by sediment inside the crevices of rocks in the littoral zone. Worms capable of swimming with strong undulating movements.

Diferential diagnosis.

We compared morphological characters of Nipponnemertes incainca sp. n. with the 18 valid species of the genus, according to Gibson (1995) and Kajihara et al. (2007) (Table 1).

The most similar species in color, arrangement of ocelli and numbers of proboscidial nerves to Nipponnemertes incainca sp. n. is N. pulchra and it might easily represent an intraspecific variation. However, in the intraspecific and interspecific genetic distance matrix (table 2), the interspecific distance between N. incainca sp. n. and N. pulchra was 21.03%, which exceeds the highest limits given by Sundberg et al. (2016b) for the Hoplonemertea. Therefore, the fact that the new species lacks the V-shape structure formed by the cephalic grooves, and the accessory stylet in the basis of the central armature, present in N. pulchra , is enough to discriminate the two species.