Paraprionospio alata ( Moore, 1923 )

Delgado-Blas, Víctor H. & Carrera-Parra, Luis F., 2018, New Phylogenetic Analysis of Paraprionospio Caullery (Polychaeta: Spionidae), with Description of a New Species from the Gulf of Mexico, Zoological Studies 57 (52), pp. 1-20 : 7-9

Paraprionospio alata ( Moore, 1923)

( Fig. 1 A-N)

Prionospio alata Moore 1923: 185-186 .

Paraprionospio alata Yokoyama 2007: 257-264 , partim.

Type material: Holotype Prionospio alata, USNM 17369, off Point Pinos Lighthouse, Monterey Bay , California, 102 m.

Redescription: Holotype incomplete with 50 chaetigers, 29 mm long, 1.6 mm wide. Color in alcohol opaque white. Prostomium fusiformshaped, frontal rounded ( Fig. 1A ), without peaks, extending posteriorly as a low raised ridge almost to chaetiger 1. Eyes not visible. Palps lost. Peristomium well developed, prolonged forward nearly to the tip of prostomium ( Fig. 1 A-B), with conspicuous, thin, translucent lateral wings ( Fig. 1B ) with rounded margins which conceal almost all prostomium. Posterior margin of each peristomial wing without a small papilla.

Branchiae present on chaetigers 1-3 ( Fig. 1C, D, G ). First pair of branchiae joined basally by prominent dorsal ridge; first pair longest, third pair shortest; first two basal branchial lamellae like plates; thereafter all lamellae flabellate. Without processes along anterior face of first branchiae, neither slender filament at the base of third branchiae.

Notopodial postchaetal lamellae well developed, elongate, subtriangular on chaetigers 1-3 ( Fig. 1 C-D), with rounded edge basally and middle on chaetigers 2-3; reniform on chaetigers 4-7 ( Fig. 1E ); lamellae longest on chaetigers 2-4 diminishing progressively in size to chaetiger 8 becoming rounded ( Fig. 1F ), thereafter becoming triangular ( Fig. 1H ) on middle and posterior chaetigers of the fragment. Dorsal crest on chaetigers 21-28, accompanied by a semi-transparent dorsal cuticle bearing circular concavities. Notopodial prechaetal lamellae well developed, elongate and fused in both edges of postchaetal and prechaetal lamellae on chaetigers 2-4 ( Fig. 1 C-E). On chaetigers 5-6 partially fused to postchaetal lamellae ( Fig. 1F ), posteriorly both lamellae free, diminishing progressively in size on middle and posterior chaetigers of the fragment.

Neuropodial postchaetal lamella triangular ( Fig. 1D ) on chaetiger 1, acuminate on chaetigers 2-3, distally more pointed on chaetiger 2 ( Fig. 1D ); rounded on chaetigers 4-12 ( Fig. 1 E-F), diminishing progressively in size to chaetiger 13, thereafter becoming like a small rounded lobe ( Fig. 1H ). Neuropodial prechaetal lamellae low, rounded. Interparapodial pouches absent. Ventral crest absent on chaetiger 8.

Anterior capillary bilimbate, long, thick with granulations ( Fig 1 I-J); posterior ones alimbate, long, thin, without granulations. Neuropodial chaetae ( Fig. 1J ) shorter and thinner than notopodial chaetae ( Fig. 1I ). Chaetiger 1 with notopodial chaetae arranged in two rows, on chaetigers 2-11 arranged in three rows, on chaetigers 12-30 in two rows, chaetae of first row shortest; thereafter arranged in one row. Chaetigers 1-22 with neurochaetae ( Fig. 1J ) arranged in two rows, chaetae of first row shortest, replaced by hooded hooks ( Fig. 1K ), posterior ones with slender alimbate capillaries ( Fig. 1L ). Sabre chaetae in neuropodia from chaetiger 9, with up to two per fascicle, big, thick, heavily granulated, without limbation ( Fig. 1M ). Neuropodial hooded hooks very small, from chaetiger 9, up to 10 per fascicle; hooks with three pairs of accessory teeth above the main tooth, and a big striated secondary hood ( Fig. 1K ); a big primary hood covers more of the half of the shaft ( Fig. 1K ). Notopodial hooded hooks from chaetiger 46, with up to 2 per fascicle, hooks with 3 pairs of accessory teeth above main tooth, and a big striated secondary hood ( Fig. 1N ).

Pygidium unknown.

Distribution: Southern California.

Remarks: Foster (1971) synonymized five species previously described as Prionospio africana Augener, 1918 , Prionospio alata Moore, 1923 , Paraprionospio tribranchiata Berkeley, 1927 , Prionospio treadwelli Hartman, 1951 (new name for Prionospio plumosa Treadwell, 1931 , which was preoccupied by Prionospio plumosa Sars, M in Sars, GO, 1872), and Prionospio ornata Berkeley and Berkeley, 1961 , and a subspecies Prionospio pinnata inaequibranchia Caullery, 1914 with Paraprionospio pinnata ( Ehlers, 1901) ; as a consequences, she considered Paraprionospio a monospecific genus. However, Fauchald (1972) provided morphological evidence to consider that Paraprionospio pinnata , P. inaequibranchia , P. africana , P. alata , and P. treadwelli should be retained as valid species.

Recently, Delgado-Blas (2004) described two new species, Paraprionospio tamaii and P. yokoyamai , from the Grand Caribbean Region. However, Yokoyama (2007) concluded that P. treadwelli , P. tamaii and P. yokoyamai are synonymies of Paraprionospio alata based on the shape of the branchial lamellae, and the presence of the dorsal crests. He redescribed Paraprionsopio alata , mixing the morphological features of the types specimens of P. alata , P. plumosa (formally P. treadwelli ), P. yokoyamai and P. tamaii . Due to this, we consider necessary the redescription of P. alata and P. plumosa based upon type material, and also the revision of the type materials of P. yokoyamai and P. tamaii to clarify the supposed synonymies of these species. After that, we found some useful features to distinguish those species as valid (see Table 3).

Paraprionospio alata differs from P. treadwelli , P. tamaii , and P. yokoyamai by having well developed lateral wings touching each other dorsally at the posterior end, while in the other three species the lateral wings are shorter. Of these species, P. treadwelli is the only species that has prostomial peaks - a new feature described in this study (see below) - and lacks secondary hood in neuro- and notopodial hooks. Paraprionospio alata and P. tamaii differ from P. treadwelli and P. yokoyamai by having the notopodial postchaetal lamellae reniform on chaetigers 4-6, whereas the other species have a subtirangular shape on the same chaetigers. However, P. alata differs of all these species by having the neuropodial postchaetal lamella reniform on the same chaetiger instead of rounded. Furthermore, P. tamaii is the only species with an unpaired accessory tooth at the distal end of the noto- and neuropodial hooded hooks, while the other species have always paired accessory teeth.

Figures

Fig. 1. Paraprionospio alata (Moore, 1923) Holotype USNM 17369. (A) Anterior region, dorsolateral view. (B) Anterior region, lateral view. (C) Parapodia of chaetigers 2-3. (D) Neuropodial lamellae, chaetigers 2-5. (E) Parapodia of chaetigers 6-8. (F) Parapodia of chaetigers 9-14. (G) Anterior region, lateral view. (H) Parapodia, posterior chaetigers. (I) Capillary notochaeta, anterior chaetiger. (J) Capillary neurochaeta, anterior chaetiger. (K) Neuropodial hooded hook. (L) Capillary neurochaeta, middle chaetigers. (M) Sabre chaetae, chaetiger 10. (N) Notopodial hooded hook, chaetiger 50. Scale bars: A, B, C, G = 1000 µm; D, E, F, H, L, N = 100 µm; I, J, K = 20 µm; M = 50 µm).