Prionospio oligopinnulata, Delgado-Blas, Víctor Hugo, 2015

Delgado-Blas, Víctor Hugo, 2015, Prionospio (Polychaeta, Spionidae) from the Grand Caribbean Region, with the descriptions of five new species and a key to species recorded in the area, Zootaxa 3905 (1), pp. 69-90 : 84-87

Prionospio oligopinnulata sp. nov.

Figure 7 A–R

Type material. GULF OF MEXICO. Campeche: Off Campeche, E46, 20º14'N, 91º05'W, Dinamo I, 17 m, 27ºC, 36.8‰, sand, 2 February 1990, holotype ( CNAP-ICML, UNAM: POH-09-002); off Campeche, E46, 20º14'N, 91º05'W, Dinamo I, 17 m, 27ºC, 36.8‰, sand, 2 February 1990, 2 paratypes ( CNAP-ICML, UNAM: POP-09- 003).

Non-type material. GULF OF MEXICO. Yucatan: Off Celestún, E30, 21º02'N, 91º05'W, Dinamo II, 31 m, 27.5ºC, 36.8‰, sand, 30 October 1990, 2 specimens ( CNAP-ICML, UNAM: PO-09-063).

Description. Holotype incomplete, 5.0 mm long for 38 chaetigers, 0.3 mm wide. Paratypes complete, 4.5–5.2 mm long for 38–40 chaetigers, 0.2–0.25 mm wide. Color in alcohol pale white. Prostomium square-shaped, truncate anteriorly ( Fig. 7 A), posteriorly tapered with short, blunt, prominent caruncle, middle slit along caruncle ( Fig. 7 A, C); caruncle extending to the anterior edge of chaetiger 2, longer than prostomium ( Fig. 7 A), with long, wide, ciliate nuchal organs ( Fig. 7 B, C) on either side ( Fig. 7 A, C). Two pairs of red-brown subdermal eyes, both pairs cup-shaped ( Fig. 7 A), arranged in a trapezoid; anterior pair small, posterior pair large and elongated ( Fig. 7 A) (holotype without eyes). Palps lost. Peristomium short ( Fig. 7 A – C), collar-like, surrounding prostomium, fused dorsally with moderately rounded notopodial lamellae on chaetiger 1 ( Fig. 7 A, C). Neuropodial postchaetal lamellae of chaetiger 1 moderate, rounded ( Fig. 7 A), much smaller than twice the size of the notopodial lamellae.

Four pairs of long branchiae present on chaetigers 2–5 ( Fig. 7 B, C). First and fourth pairs longest ( Fig. 7 B, C), generally first pair longer: up to 5 times the size of the fourth pair, but pairs 1 and 4 sometimes equal in length; pairs 1 and 4 with a few short, digitiform pinnules on the lateral face, branchiae with long naked, smooth distal tips ( Fig. 7 B, C). Distribution of pinnules on these two pairs similar, pinnules few, sparsely distributed in the middle of the branchiae ( Fig. 7 B, C); central stems of pairs 1 and 4 of the branchiae pinnate, elongate, pair 1 slightly ciliated laterally ( Fig. 7 B). Pairs 2 and 3 apinnate, triangular, narrow, with dense lateral ciliation and sharp tips ( Fig. 7 B, C); subequal in length, shorter than the pinnate pairs, but longer than the notopodial lamellae ( Fig. 7 B, C).

Notopodial postchaetal lamellae triangular, slender on chaetigers 2–6, with wide bases, thin from half way up and elongated ( Fig. 7 B, D, E), largest on chaetigers 3–4; lamellae of chaetiger 7 subtriangular with blunt tips ( Fig. 7 B, F), progressively decreasing in size and becoming rounded on chaetigers 9–10 ( Fig. 7 G). Notopodial lamellae united across dorsum, forming high dorsal crests ( Fig. 7 J) on chaetigers 7–8 (one specimen with a low fold on chaetiger 8) ( Fig. 7 B), and low dorsal folds on chaetigers 9–14 ( Fig. 7 B, J); lamellae on posterior chaetigers small, rounded ( Fig. 7 H, I). Ventral and dorsal edges of notopodial and neuropodial lamellae not touching on anterior chaetigers ( Fig. 7 C, D). Notopodial prechaetal lamellae low in branchial region, not basally fused with notopodial postchaetal lamellae ( Fig. 7 A, D, E), becoming rounder and smaller on far posterior chaetigers ( Fig. 7 I).

Neuropodial postchaetal lamellae on chaetigers 2–3 large, subtriangular, ventrally pointed ( Fig. 7 C, D), becoming rounded on chaetigers 4–5 ( Fig. 7 D, E); gradually decreasing in size on following chaetigers ( Fig. 7 F – H), smallest on far posterior chaetigers ( Fig. 7 I). Neuropodial prechaetal lamellae rounded, small in anterior region ( Fig. 7 D – F), rudimentary throughout. Interparapodial pouches lacking.

Anterior chaetae all heavily granulated and with very long capillary tips ( Fig. 7 K, L); notopodial chaetae slightly unilimbate ( Fig. 7 K), neuropodial chaetae alimbate ( Fig. 7 L); notopodial and neuropodial capillaries arranged in two rows from chaetiger 1 onwards, with short, thin chaetae, notopodial chaetae longer with the posterior row longest; chaetae from chaetiger 18 arranged in one row, chaetae thin, without granulations and with very long capillary tips ( Fig. 7 M). Neuropodia from about chaetiger 10 also arranged in one row, chaetae thin, without granulations and with very long capillary tips ( Fig. 7 N); dorsal chaetae long and ventral chaetae short; posterior notopodia with thinner and shorter chaetae than middle notopodia. Sabre chaetae in neuropodia from chaetiger 10, one per fascicle, moderately granulated and without sheaths ( Fig. 7 O). Neuropodial hooded hooks ( Fig. 7 P) from chaetigers 12–14 (holotype: 12), up to seven per fascicle, alternating with thin capillaries, posterior hooks accompanied by up to two capillaries. Notopodial hooded hooks from chaetigers 23–39 (holotype: 30) ( Fig. 7 Q) equal in length to neuropodial hooks, but slenderer and fewer per fascicle; up to four per fascicle, accompanied by up to four thin capillaries; all hooks with four pairs of small teeth above main tooth and conspicuous secondary hood ( Fig. 7 P, Q).

Pygidium with one long, thin median cirrus and two short lateral lobes ( Fig. 7 R).

Remarks. Examination of the other species in the steenstrupi -group ( Sigvaldadóttir & Mackie, 1993: Table 2; Blake, 1996; Sigvaldadóttir 1997; Zhou & Li 2009) shows that Prionospio oligopinnulata nov. sp. is most similar to P. depauperata Imajima 1990 and P. kulin Wilson 1990 as all three species have subtriangular, ventrally pointed neuropodial postchaetal lamellae on chaetigers 2–3 and dorsal crests on several chaetigers. However, P. oligopinnulata differs from P. depauperata in that in the former the prostomium is truncated anteriorly, the notopodial and neuropodial lamellae on chaetiger 1 and on the posterior parapodia are rounded, low dorsal folds are present from chaetigers 9–14, the anterior notopodial chaetae are slightly unilimbate and the neuropodial chaetae alimbate, the sabre chaetae lack sheaths, neuropodial hooded hooks are present from chaetigers 12–14 and notopodial hooded hooks from chaetigers 23–33, and all hooks have four pairs of small teeth above the main tooth. Prionospio oligopinnulata differs from P. kulin in that the former has a long, blunt, prominent caruncle, well developed parapodial lamellae on chaetiger 1, rounded posterior neuropodial lamellae, low dorsal folds on chaetigers 9–14, an absence of interparapodial pouches, and hooks with four pairs of small teeth above the main tooth all with a secondary hood. Prionospio oligopinnulata also differs from P. k ul i n and P. depauperata in that it has a slit along the middle of the caruncle. The differences between this new species and the other species examined are provided in the key and Table 1.

Etymology. The specific name is from the Greek oligo meaning few and refers to the few pinnules distributed scarcely on the branchiae.

Type locality. Gulf of Mexico Campeche, Yucatán.

Figures

FIGURE 7. Prionospio oligopinnulata sp. nov., holotype (CNAP-ICML, UNAM: POH- 09 - 002: (A, D – R); paratype (CNAP- ICML, UNAM: POP- 09 - 003: B – C) SEM micrographs: (A) anterior region, dorso-lateral view; (B) anterior region, dorsal view; (C) anterior region, dorso-lateral view; (D) parapodium of chaetigers 2 – 4 and branchiae of chaetiger 3; (E) parapodium of chaetiger 5; (F) notopodium of chaetiger 8; (G) parapodium of chaetiger 10; (H) parapodium of chaetiger 25; (I) parapodium of chaetiger 39; (J) high dorsal crests and low folds on chaetigers 7 – 11; (K) anterior notopodial chaeta; (L) anterior neuropodial chaeta; (M) middle notopodial chaeta; (N) middle neuropodial chaeta; (O) sabre chaeta; (P) neuropodial hooded hook; (Q) notopodial hooded hook; (R) pygidium, dorsal view. Scale bars: A, J 80 µm; B 100 µm; C 43.4 µm; D – E, K – N, R 50 µm; F – G, P – Q 30 µm; H – I 20 µm; O 0.5 µm.