Prionospio crassumbranchiata, 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 : 73-76

Prionospio crassumbranchiata sp. nov.

Figures 2 A – F, 3A – L

Material examined. GULF OF MEXICO. Veracruz: Off the coast of Coatzacoalcos, E11, 18º44'N 94º41.9'W; 173 m, muddy, 8 August 1984, coll. E. Donath Hernández, holotype (LACM-AHF-POLY 6597); Tabasco: Off the coast of Paraiso, E7, 18º30'N, 93º36'W, IMCA II, 29 m, 27.2ºC, 36.1‰, org. carb. 0.120%, muddy-sand, 1 paratype ( CNAP-ICML, UNAM: POP-09-002); Campeche: Off Cayo Arcas, E51, 19º59'N, 92º11'W, IMCA II, 188 m, 16.3 ºC, 36.2 ‰, muddy, 24 September 1988, 2 paratypes ( CNAP-ICML, UNAM: POP-09-002); off Cayo Arcas, E51, 19º59'N, 92º11'W, 188 m, 16.3ºC, 36.2‰, muddy, 24 September 1988, 1 paratype ( CNAP-ICML, UNAM: POP-09-002).

Description. Holotype incomplete, 9.0 mm long; consists of one fragment with 30 chaetigers, 1.2 mm wide. Paratypes incomplete 6.6–9.1 mm long, with 28–34 chaetigers, 1.2–1.3 mm wide. Color in alcohol pale white. Prostomium bottle-shaped, truncate on anterior margin ( Fig. 2 A, 3A), posteriorly tapered, with short, narrow caruncle extending to the anterior edge of chaetiger 2 ( Fig. 2 A, 3A) with large triangular nuchal organs on either side ( Fig. 2 A, 3A). Eyes absent ( Fig. 3 A). One paratype with two pairs of subdermal brown eyes arranged in a trapezoid; anterior pair crescent-shaped; posterior pair small, rounded. Palps lost, except in one specimen with a pair of palps inserted anterior to the nuchal organs: the left palp in the process of regeneration and the right palp fragmented and in bad condition, with a short basal sheath ( Fig. 2 A–C). Peristomium long, collar-like, surrounding the prostomium, laterally separate ( Fig. 2 B), partially fused dorsally with very large rounded notopodial lamellae on chaetiger 1 ( Fig. 3 A). Neuropodial postchaetal lamellae of chaetiger 1 very large and rounded ( Fig. 2 B), smaller than notopodial lamellae.

Four pairs of short branchiae present on chaetigers 2–5, the first pair longest and thickest ( Fig. 3 A); sometimes the first and fourth pairs equal in length. First pair with long, dense digitiform pinnules on the lateral and posterior faces, and with short naked, smooth distal tips; distribution of the pinnules basally to distally: all pinnules arranged in curved rows ( Fig. 3 B, C), in the basal and middle regions with up to 7 pinnules per row ( Fig. 3 C) and in the distal region with 3 pinnules per row; the central stem of branchial pair 1 pinnate, cylindrical, very thick and with a blunt tip ( Fig. 3 A). Pairs 2–4 apinnate; pairs 2 and 3 triangular, broad ( Fig. 2 A, 3A), densely ciliated laterally, with short, sharp tips; subequal in length to the notopodial lamellae, shorter than pinnate pair. Pair 4 cirriform ( Fig. 2 A), basally united by a short, low dorsal fold; subequal or longer than notopodial lamellae.

Notopodial postchaetal lamellae triangular with triangular tips widest on chaetigers 2–6 ( Fig. 2 A); largest on chaetigers 3–5; lamellae of chaetigers 7–10 subtriangular ( Fig. 2 C). Lamellae gradually becoming smaller, rounder and more dorsally directed from chaetigers 15–16 ( Fig. 2 C, D); lamellae of posterior chaetigers rounded ( Fig. 3 D).

Notopodial postchaetal lamellae united, forming low dorsal crests from chaetigers 5–6 ( Fig. 2 A, 3A), and continuing as very low folds up to about chaetiger 23–31 ( Fig. 2 C, D). Ventral and dorsal edges of notopodial and neuropodial lamellae not touching on anterior chaetigers ( Fig. 2 D). Notopodial prechaetal lamellae moderately sized in the branchial region, not fused basally with the notopodial postchaetal lamellae, posterior chaetigers rudimentary.

Anterior neuropodial postchaetal lamellae large, rectangular with rounded edges ( Fig. 2 B); more angular and dorsally directed on chaetigers 3–4 ( Fig. 3 E); rectangular, slightly more slender and ventrally directed on chaetigers 5–6 ( Fig. 3 F); subsequent neuropodial lamellae rounded ( Fig. 2 D, E, 3G, H,) and small on far posterior chaetigers. Neuropodial prechaetal lamellae small in branchial region ( Fig. 2 B), rudimentary throughout. Interparapodial pouches on chaetigers 4–20/21 non-reticulated ( Fig. 2 D, E).

All capillaries on anterior chaetigers alimbate, thin, granulated ( Fig. 3 I, J); notopodial and neuropodial capillaries of chaetiger 1 arranged in two rows, with short, thin chaetae; notopodial chaetae longer ( Fig. 3 I). Notopodial capillaries of chaetigers 2–11 arranged in three rows, anterior row shorter than posterior rows; middle notopodial capillaries granulated, arranged in two rows of chaetae, dorsal chaetae very long and acute ( Fig. 3 I), ventral chaetae very short and acute; neuropodial capillaries in two rows, chaetae very long, acute, granulated ( Fig. 3 J), first row much shorter; posterior capillaries thin and smooth. Sabre chaetae in neuropodia from chaetiger 19–20, up to three per parapodium ( Fig. 2 F), each chaeta stout, faintly granulated distally, with slightly limbate tips, long ( Fig. 3 K). Neuropodial hooded hooks ( Fig. 3 L) from chaetigers 20, up to 13 per fascicle, accompanied by up to 10 capillaries; all hooks with six pairs of small teeth ( Fig. 3 L) above small main tooth; hooks appear to possess very striated secondary hoods, producing a feathered effect below the main fang ( Fig. 3 L); neuropodial hooks with large principal hood, ventral hooks shorter than the dorsal hooks ( Fig. 2 F). Notopodial hooded hooks not observed up to chaetiger 34.

Pygidium not known.

Remarks. Prionospio crassumbranchiata sp. nov. is closely related to P. ehlersi Fauvel, 1928 and P. saccifera Mackie & Hartley, 1990 in that it has the same shaped prostomium, branchial arrangement, presence of interparapodial pouches and structure of hooded hooks. However, Prionospio crassumbranchiata sp. nov. can be distinguished from the original description of P. ehlersi Fauvel,1928 , and the redescription of P. ehlersi by Mackie & Hartley (1990) and P. saccifera in that in P. crassumbranchiata , the peristomium is laterally separate, but partially fused dorsally with the first chaetiger; the first pair of branchiae have long, dense, digitiform pinnules on their lateral and posterior faces; the neuropodial lamellae of chaetiger 2–5 are rectangular, more angular, and dorsally directed; the neuropodial prechaetal lamellae on the middle chaetigers are short; all the capillaries on the anterior chaetigers are alimbate; the sabre chaetae have slightly limbate tips; all hooks have six pairs of small teeth above the main tooth and the sabre chaetae start on chaetiger 20. P. crassumbranchiata differs from P. saccifera in that the notopodial lamellae of chaetiger 1 are rounded; the first branchial pair is not united basally by a short, low dorsal crest; the interparapodial pouches start on chaetigers 4; branchial pairs 2–3 are apinnate, triangular, shorter, with short sharp tips. Prionospio crassumbranchiata sp. nov. also differs from the redescription of P. ehlersi by Maciolek (1985) in that the former has a bottle-shaped, anteriorly truncate prostomium; no eyes; low dorsal folds; rectangular anterior neuropodial postchaetal lamellae with rounded edges, more angular and dorsally directed on chaetigers 3–4, rectangular, slightly more slender and ventrally directed on chaetigers 5–6 and interparapodial pouches from chaetiger 4. Whereas, the specimens described by Maciolek have a rectangular prostomium that is narrower in the middle region and broadly rounded anteriorly ( Maciolek, 1985: 345: Fig, 7); they also have the presence of eyes; a high dorsal crest; rounded neuropodial lamellae and interparapodial pouches starting from chaetigers 2–5 making them different from P. crassumbranchiata sp. nov. The differences between this new species and the other species examined are provided in the key and table 1.

Type locality. South of the Gulf of Mexico: Veracruz, Tabasco and Campeche.

Etymology. The specific name is from the Latin crassum meaning thick and refers to the thickness of the first pairs of branchiae.

Characters P. austella sp. nov. P. crassumbranchiata P. cristata Foster P. jonatani sp. nov. P. oligopinnulata sp. P. rotunda sp. nov.

sp. nov. 1971; Maciolek 1985 nov. [], this paper ()

Measurement (mm): Anterior fragment: Anterior fragments: a. 7.1 [6, 0.3] (12.0– a. 16–23, 0.2–0.6 a. 4.5-5.2, 0.2–0.3 a. 5.0–5.5, 0.2

Length, width a. 17, 1.0 a. 6.6–9.1, 1.2-1.3 14.0, 0.4–0.5) b. 72–79 b. 38–40 b. 45–49

No. of chaetigers b. 51 b. 28–34 b. 33 [42] (59–65)

Prostomium Bottle-shaped, Bottle-shaped, Subtriangular, Skittle-shaped, Square-shaped, Pyriform-shaped, anteriorly trucante, anteriorly truncate anteriorly rounded anteriorly narrow, anteriorly truncate anteriorly rounded with a small medial rounded

peak

pairs of eyes a. Crescent-shaped Absent or a. Rounded Absent a. Cup-shaped Absence or

Anterior pair b. Large eyespots a. Crescent-shaped b. Crescent-shaped b. Cup-shaped a. Rounded

Posterior pair b. Rounded b. Cup-shaped

Caruncle Long, narrow Short, narrow Short, blunt Short, narrow Short, blunt and Long, blunt prominent, with a middle slit along caruncle

Shape of nuchal Absent (not observed) Triangular; on both (Long; on both sides Large, V-shaped; on Long and wide; on Fused over both sides

organs; position sides of caruncle of caruncle) [may both sides of caruncle both sides of caruncle of caruncle

respect to the caruncle extend across

caruncle]

Peristomium Moderate Long Short Short Short Moderate

Relative length of 1>4 1>, =4 1>, =4 1>4 1>, =4 1>4

pinnate branchial pairs

and 4

Shape of apinnate Triangular, broad Triangular, broad Cirriform Triangular, broad Triangular, narrow Cirriform

branchial pairs 2 and 3

Notopodial postchaetal Rounded, large Rounded, very large Rounded, large Rounded, very large Rounded, moderate Rounded, large

lamellae (chaetiger 1)

Notopodial and Touching chaetiger 3 Not touching anterior (Not overlapping or Not overlapping or Not touching anterior Not overlapping or

neuropodial lamellae chaetigers touching) touching chaetigers touching overlaps or

touching

High dorsal crests a. Absent a. 5–6 a. 7–9 a. Absent a. 7 & 8 a. 7

Low dorsal folds b. 6–11 b. 7–23/31 b. 10–11 b. Absent b. 9–14 b. Absent

......continued on the next page Characters P. austella sp. nov. P. crassumbranchiata P. cristata Foster P. jonatani sp. nov. P. oligopinnulata sp. P. rotunda sp. nov.

sp. nov. 1971; Maciolek 1985 nov. [], this paper ()

Anterior notopodial Very large on Moderate Large in branchial Moderate in branchial Low Very low

prechaetal lamellae chaetigers 2-7 region region

Anterior neuropodial a. Subtriangular, a. Rectangular, more a. Rounded [squarish] a. Square a. Subtriangular, a. Subtriangular,

postchaetal lamellae ventrally pointed angular, dorsally b. Angled, trapezoid, b. Square ventrally pointed ventrally pointed Chaetiger 2 b. Subtriangular, directed dorsally directed c. Square b. Subtriangular, b. Trapezoid, slightly Chaetiger 3 ventrally pointed b. Same as above [squarish] d. Square ventrally pointed dorsally pointed Chaetiger 4 c. Oval c. Same as above c. Rounded [squarish] c. Rounded c. Rounded Chaetiger 5 d. Oval d. Same as above d. Rounded d. Rounded d. Rounded [squarish]

Anterior neuropodial Large Low Moderate Very low Low Very low

prechaetal lamellae

Interparapodial Absent Present Absent Absent Absent Absent

pouches

Anterior notopodial Thicker, alimbate, Alimbate [Bilimbate]and Unilimbate, with very Slightly unilimbate Very long and very

chaetae with very long unilimbate (Very long capillary tips acute, unilimbate

capillary tips long and very acute,

unilimbate)

Anterior neuropodial Thick, alimbate, with Alimbate [Bilimbate] Unilimbate Alimbate Short and very acute,

chaetae very long capillary (unilimbate, very alimbate tips long and very acute)

Sabrechaetae 10 19–20 10 14–18 10 10

Neuropodial hooded a. 16 a. 20 a. 11–12 [10–13] a. 16–28 a. 12–14 a. 11–12

hooks b. 4 b. 6 (12–13) b. 4 b. 4 b. 4 Start on chaetiger c. Absent c. Very striated b. 4 c. Absent c. Conspicuous c. Conspicuous No. of pairs of c. Conspicuous

accessory teeth

Secondary hood

Notopodial hooded a. 46? a.21–37 (26–34) a. 35–77 a. 23–39 a. 28–32

hooks b. 4 b. 4 b. 4 b. 4 b. 4 Start on chaetiger c. Absent c. Conspicuous c. Absent c. Conspicuous c. Conspicuous No. of pairs of

accessory teeth

Secondary hood

Figures

FIGURE 2. Prionsopio crassumbranchiata sp. nov., paratype (CNAP-ICML, UNAM: POP- 09 - 002: A – F) SEM micrographs: (A) anterior region, dorsal view; (B) anterior region, lateral view with palp; (C) anterior and middle region, dorsal view; (D) anterior region, dorso-lateral view; (E) interparapodial pouches; (F) sabre chaetae and neuropodial hooks. Scale bars: A 142 µm; B, E 100 µm; C – D 333 µm; F 25.0 µm.

FIGURE 3. Prionospio crassumbranchiata sp. nov., holotype (LACM-AHF-POLY 6597): (A) anterior region, dorsal view; (B) cross section of branchiae with pinnules; (C) branchial pinnules arranged in a curved row; (D) notopodium of chaetiger 16; (E) neuropodium of chaetiger 3; (F) neuropodium of chaetiger 5; (G) neuropodium of chaetiger 7; (H) neuropodium of chaetiger 9; (I) capillary notochaeta of anterior chaetiger; (J) capillary neurochaeta of anterior chaetiger; (K) sabre chaeta; (L) neuropodial hooded hook. Scale bars: A 700 µm; B – C 80 µm; D – H 100 µm; I – K 100 µm; L 50 µm.