Alitta Kinberg, 1865

Villalobos-Guerrero, Tulio F. & Carrera-Parra, Luis F., 2015, Redescription of Alitta succinea (Leuckart, 1847) and reinstatement of A. acutifolia (Ehlers, 1901) n. comb. based upon morphological and molecular data (Polychaeta: Nereididae), Zootaxa 3919 (1), pp. 157-178 : 160

Alitta Kinberg, 1865

Alitta Kinberg, 1865: 172 ; Malmgren 1865: 183; Khlebovich 1996: 108 −109; Bakken & Wilson 2005: 514 −516 (partim).

Type species: Nereis virens Sars, 1835 , by monotypy.

Gender: Feminine.

Diagnosis (modified from Bakken & Wilson 2005). Prostomium with entire anterior margin, two antennae, two palps with conical palpostyles, four pairs of tentacular cirri with distinct cirrophores. Two pairs of eyes. One apodous anterior segment larger than length of chaetiger 1. Maxillary ring of pharynx with conical paragnaths; areas I −IV, present. Oral ring with conical paragnaths and occasionally p-bar or pyramidal paragnaths; area V, present or absent; VI −VIII, present. Dorsal ligule elongated pennant-like or wide cordate in posterior chaetigers. Prechaetal notopodial lobe long on anterior chaetigers, present at least on anterior and middle chaetigers. Dorsal cirri mid-dorsally to terminally attached to dorsal ligule in posterior chaetigers. Neuropodial postchaetal lobe projecting beyond end of acicular ligule, present throughout, digitiform. Notoaciculae absent or present from chaetigers 1 and 2. Neurochaetae upper fascicle with homogomph spinigers; heterogomph falcigers on anterior chaetigers present, on posterior ones absent or present. Neurochaetae lower fascicle with heterogomph spinigers and heterogomph falcigers present. Heterogomph falcigers may have terminal tendon.

Remarks. Kinberg (1865) recognized Nereis Linnaeus, 1758 and his new genus Neanthes by having similar parapodia in all chaetigers, but the latter with paragnaths in all areas. Likewise, Kinberg established Alitta for N. virens by having “foliose and dilated” dorsal ligule, paragnaths in all the areas of pharynx and only spinigers. Malmgren (1865, 1867) synonymized some taxa proposed by Kinberg using parapodial features; furthermore, he described A. brandti but maintained the combination of A. virens . However, Ehlers (1868) dismissed these differences and included all Kinberg and Malmgren’s genera with paragnaths in Nereis . Claparède (1870) preferred to separate Nereis in subgenera, and following this idea, von Marenzeller (1879) described N. (Alitta) oxypoda from Japan, a species related to those species included by Malmgren in Alitta . de Saint-Joseph (1898), as did Claparède (1870), proposed additional subgenera in Nereis based upon the presence of conical paragnaths; thus, he regarded that N. ( Neanthes ) includes Alitta by having paragnaths present in all regions of the pharynx. Afterwards, some authors recognized or not recognized the (sub) generic level of Nereis and Neanthes (e.g., Ehlers 1901; Horst 1909; Heinen 1911; Fauvel 1912, 1919, 1923 a, b, 1936; Rioja 1918; Hartman 1936); meanwhile, Alitta remained as a junior synonym. Later, Hartman (1940) modified the subgeneric level to differentiate between Nereis and Neanthes ; the latter, which included N. succinea , was characterized by lacking notopodial falcigers and by having an elongated prechaetal notopodial lobes. Imajima (1972) proposed Nectoneanthes and transferred N. oxypoda and N. ijimai Izuka, 1912 to this new genus, both of which differed from Neanthes by lacking neuropodial falcigers. Wilson (1988) regarded the upper lobe of dorsal ligule and the absence of falcigers in N. oxypoda as epitokal changes of N. succinea ; therefore, he synonymized Nectoneanthes with Neanthes . In contrast, Khlebovich (1996) retained N. succinea in Neanthes due to the presence of a pennant-like dorsal ligule on posterior chaetigers; likewise, he re-established Alitta and Nectoneanthes based on presence of wide, foliose dorsal ligule on posterior chaetigers, but with an ovoid lobe projected over the dorsal cirrus in the latter. Santos et al. (2005) supported the validity of Nectoneanthes without delving into the topic, but excluded Alitta in the phylogeny of nereidids. The same year, Bakken & Wilson (2005) combined N. succinea in Alitta through a morphological phylogenetic analysis, and once again synonymized Nectoneanthes following Wilson (1988). Thus, they emended Alitta and defined the genus by having a notopodial prechaetal lobe as long as the dorsal ligule and neuropodial postchaetal lobe on all chaetigers of the body. Sato (2013) re-established Nectoneanthes based on type material of N. oxypoda , and transferred A. succinea to Neanthes by having notoaciculae in chaetigers 1 and 2. However, this feature does not define Alitta (fide Bakken & Wilson 2005: 516); hence, we consider Sato’s generic placement as invalid because of generic definitions (see above). We retain succinea in Alitta , including A. acutifolia n. comb., A. brandti , A. grandis ( Stimpson, 1853) and the “ A. succinea ” and “ A. virens ” species complexes with their related species.