Marphysa viridis Treadwell, 1917

Molina-Acevedo, Isabel C. & Carrera-Parra, Luis F., 2015, Reinstatement of three species of the Marphysa sanguinea complex (Polychaeta: Eunicidae) from the Grand Caribbean Region, Zootaxa 3925 (1), pp. 37-55 : 48-50

Marphysa viridis Treadwell, 1917

Figures 7–10

Marphysa viridis Treadwell, 1917: 264 –265, Pl. 2, Figs 13–18; Pl. 3, Figs 1–2 ; 1921:64–66, Pl. 6, Figs 1–4 , text-figs 212–223. Marphysa sanguinea Salazar –Vallejo & Carrera– Parra, 1998: 1493 –1494, Figs 8 a–e, 9. (non Montagu, 1815)

Material examined. Type material: Holotype AMNH VI–1915 –1293, Boca Grande Key, Florida, 24°31'N 82°00''W, Jul 1915. Additional material: Gulf of Mexico: ECOSUR-P2676 (1), Jaina Island, Campeche, Mexico, 20°12'34.6'' N 90°29'12.5'' W, 27 May 2005, 1 m, 10 m from coast line, in black rough sponge. ECOSUR-P2677 (6) Cerritos Island, Yucatán, Mexico, 21°33'45.97'' N 88°17'03.40'' W, 18 Jan 1991, 0.5 m, under rocks. Mexican Caribbean: ECOSUR-P2678 (3) Beach Las Garzas, Contoy Island, 21°29'53'' N 86°48'09'' W, 24 Feb 2008. ECOSUR-P2679 (1) Yalahau Lagoon, Quintana Roo, 21°30'44'' N 87°12'24'' W, 0 8 Sep 1993, 1 m, in macroalgae. ECOSUR-P2680 (3), Tres Marías Island, Ascensión bay, Quintana Roo, 19°36'43'' N 87°31'0''W, 28 Apr 1987, in mangrove root. ECOSUR-P2681 (1), Nichupté Lagoon, Cancún, Quintana Roo, sta. NC1E3, 21 °06'54'' N 86°45'41'' W, 29 Oct 1987, 1 m. ECOSUR-P2682 (4) Nichupté Lagoon, Cancún, Quintana Roo, sta. NC1E6, 21 °04'28'' N 86°46'48'' W, 28 Oct 1987, 1 m. ECOSUR-P2683 (2), Nichupté Lagoon, Cancún, Quintana Roo, sta. NC2E6, 21 °04'28'' N 86°46'48'' W, 0 2 Feb 1988, 1 m. ECOSUR-P2684 (5), Nichupté Lagoon, Cancún, Quintana Roo, sta. NC3E5, 21 °06'54'' N 86°45'41'' W, 19 Apr 1988, 1 m. ECOSUR-P2685 (5), Nichupté Lagoon, Cancún, Quintana Roo, sta. NC3E8, 21 °06'54'' N 86°45'41'' W, 20 Apr 1988, 1 m. ECOSUR-P2686 (2), Nichupté Lagoon, Cancún, Quintana Roo, sta. NC4E3, 21 °06'54'' N 86°45'41'' W, 0 5 Jul 1988, 1 m.

Description. Holotype complete, with 198 chaetigers, L10= 11 mm, W10= 3.5 mm, TL= 95 mm. Anterior region with convex dorsum, venter flat, without groove; body depressed from chaetiger 5, widest at chaetiger 23, tapering after chaetiger 24. Treadwell (1917) described the live specimen with prostomium and first peristomial ring markedly greenish.

Prostomium bilobed, 1.5 mm long, 2.5 mm wide; lobes frontally rounded; median sulcus shallow ( Fig. 7 A), ventral sulcus deep. Prostomial appendages in semicircle, median antenna isolated by gap. Palps reaching middle of first peristomial ring; lateral antennae reaching anterior end of first chaetiger; median antenna reaching first chaetiger. Palpophores and ceratophores ring-shaped, short, thick; palpostyles and ceratostyles tapering, without articulation. Eyes rounded, dark, between palps and lateral antennae.

Peristomium longer and wider than prostomium (2.2 mm long, 3.3 mm wide), first ring three times longer than second ring; separation between rings distinct on all sides ( Fig. 7 A). Inferior lip with a shallow central depression with a couple of shallow wrinkles ( Fig. 7 B).

Maxillary apparatus lost. MF= 1+1, 5+6, 8+0, 4+7, 1+1 according to Treadwell (1921: 264–265, Fig. 1 , Pl. 3). In a non-type specimen (ECOSUR-P2677) MF= 1+1, 7+6, 8+0, 5+9, 1+1 ( Fig. 7 C). Maxillary carriers 4 times shorter than MI, anterior region rectangular, posterior end triangular, with a pair of oval wings situated at the lateral margins of maxillary carriers. MI forceps-like, without attachment lamella; maxilla with falcal arch at right, poorly developed ( Fig. 7 C). Closing system 6 times shorter than MI ( Fig. 7 C); ligament between MI and MII rectangular, dark. MII wide, without attachment lamella; distal tooth bigger, directed laterally, other teeth recurved; cavity opening oval, 4.5 times shorter than MII; ligament between MII and MIII and right MIV slightly sclerotized ( Fig. 7 D). MIII short, curved, forming part of distal arc; with blunt teeth, basal tooth smaller; with rectangular attachment lamella, situated in the center of posterior edge of maxilla ( Fig. 7 D). Left MIV with second tooth larger, last two teeth smaller; attachment lamella semicircular, better developed in central portion, situated 2/3s of distance from posterior end of maxilla ( Fig. 7 D). Right MIV with blunt teeth, three last teeth smaller; attachment lamella wide, better developed in the middle, situated 3/4s of distance from posterior edge. MV rectangular, slightly longer than wide, with a short rounded tooth ( Fig. 7 C). Mandibles dark; with whitish cutting plates, with around 13–15 growth rings ( Fig. 7 E).

Branchiae pectinate with up to 5 filaments, present from chaetigers 22L–23R to 175L–174R ( Fig. 8 C–D). First pair and last 10 with one filament; with five filaments in chaetigers 70–101 ( Fig. 10 ). Branchial filaments longer than dorsal cirri.

First three parapodia smaller; best developed along chaetigers 4 to 30, following ones becoming gradually smaller. Notopodial cirri without articulation; slightly longer than ventral cirri, tapering, best developed in chaetigers 4–11, posterior ones gradually decreasing in size, being smaller, conical about chaetiger 34 ( Fig. 8 A–E). Prechaetal lobes short, as transverse fold in all chaetigers ( Fig. 8 A–E). Chaetal lobes from chaetigers 1 to 52 almost rectangular, slightly longer at ventral edge, with aciculae emerging dorsal to midline, shorter than postchaetal lobes; from chaetiger 53 with prominent dorsal expansion where aciculae emerge; posterior to chaetiger 144, rounded with acicula emerging dorsally to midline, longer than other lobes ( Fig. 8 A–E). Postchaetal lobes well developed from chaetigers 1 to 51, posterior ones inconspicuous; first five digitiform, along chaetigers 6 to 51 rounded, posterior ones inconspicuous ( Fig. 8 A–E). Ventral cirri in chaetigers 1–15 ovate; from chaetigers 16 to 175 with oval swollen base and digitiform tip; posterior ones digitiform ( Fig. 8 A–E).

Aciculae blunt, reddish with distal end translucent; with up to 4 in first 18 chaetigers, from chaetiger 19 with 2 or 3 aciculae; from chaetiger 141 with only one.

Most chaetae broken. Chaetae limbate supracicular of two sizes in the same chaetiger, longer dorsally, less abundant from chaetiger 22. Three types of pectinate chaetae: Isodonts narrow with short and fine teeth, in anterior chaetigers with 2–3 pectinate chaetae, with up to 14 teeth ( Fig. 8 G). Isodonts wide with short and fine teeth, in median chaetigers with 2–3 pectinate chaetae with up to 20 teeth ( Fig. 8 H), in posterior ones with 4–5 pectinate chaetae with up to 14 teeth. Anodonts wide with long and thick teeth, in median chaetigers with 3–4 pectinate chaetae, with up to 8 teeth, in posterior ones with 4–5 pectinate chaetae, with up to 10 teeth ( Fig. 8 I). Compound spinigers present in all chaetigers ( Fig. 8 J), blades of two sizes in same chaetiger, shorter in anterior region of chaetiger. Subacicular hooks bidentate, yellow, beginning from chaetigers 37R–38L, always one per chaetiger. Proximal and distal teeth worn, rounded. In non-type specimen, distal tooth smaller than proximal tooth, directed upward; proximal tooth triangular, directed frontally ( Fig. 8 F).

Pygidium with two pairs of pygidial cirri, without articulation; dorsal pair as long as last four chaetigers; ventral pair short, as long as last chaetiger.

Variation. Material examined varied in L10 from 2 to 10.2 mm, and in W10 from 1 to 5 mm and varies in the following features: palps reaching first peristomial ring or chaetiger 1; lateral antennae reaching chaetiger 1–3; median antenna reaching chaetiger 2–4. Maxillary formula varies as follows: MII: 4–5+4–5, MIII: 5–8, MIV: 3–5+7–10. Start of branchiae varies from chaetigers 17 to 25, last chaetigers without branchiae from 23 to 50. We observed a slight tendency in the beginning of branchiae with respect to the size; smaller specimens have branchiae from chaetiger 17, while larger specimens from chaetiger 25. Number of maximum branchial filaments varies from 2 to 6, it is a length-dependent feature (R²= 0.74, n= 23; Fig. 9 A). Last well developed postchaetal lobe varies from chaetigers 27 to 52; it is a length-dependent feature, ending later in larger specimens (R2=0.57, n= 33, Fig. 9 B). Last ventral cirrus with swollen base varies from 23 to 54 chaetigers before pygidium; it is also a length-dependent feature, ending later in larger specimens (R2= 0.93, n= 9, Fig. 9 C). Subacicular hooks start from chaetigers 21 to 42, and it is a length-dependent feature, beginning later in larger specimens (R2= 0.57, n= 33; Fig. 9 D).

Habitat. In sandy mud, low-water mark ( Treadwell, 1917), in mangrove roots, macroalgae, sponges, seagrass or under rocks.

Distribution. Mangrove Key, Key West Harbor, Boca Grande and Marquesa Key, Florida; southern Gulf of Mexico and Mexican Caribbean.

Discussion. Marphysa viridis belongs to group B2 ( Fauchald 1970); it is close to M. acicularum , M. brasiliensis (from Brazil), M. elityeni (from South Africa), M. mullawa (from Australia), and M. sanguinea (from England) by having spinigers present in all chaetigers and bidentate subacicular hooks. Marphysa viridis , M. mullawa and M. sanguinea have two types of wide pectinate chaetae (isodont and anodont); however, M. viridis has an additional type, isodont narrow pectinate chaetae. In addition, M. sanguinea and M. viridis differ in the number of teeth in MIII and right MIV; the former has 4–6 teeth in MIII and 5–8 in right MIV, while the latter has 5–8 teeth in MIII and 7–10 in right MIV. The species also differ in the shape of the postchaetal lobes and the beginning of subacicular hooks; in M. viridis , the postchaetal lobe is rounded and subacicular hooks start from chaetiger 37 (specimen with 198 chaetigers), while in M. sanguinea the postchaetal lobe is triangular and subacicular hooks start from chaetiger 21 (specimen with 290 chaetigers). Marphysa elityeni reaches large lengths (170–850 mm), which may explain the late start of branchiae (chaetigers 36–42), and subacicular hooks (chaetigers 60–70); in contrast, our longest specimens of M. viridis are shorter (around 100 mm), having an early beginning of branchiae (chaetigers 17–25), and subacicular hooks (chaetigers 21–42). In addition, both species differ in the type of isodont pectinate chaetae; M. elityeni has only wide pectinate chaetae, whereas M. viridis has both narrow and wide pectinate chaetae. Furthermore, M. viridis (TL= 95 mm) differs from M. brasiliensi s (LT= 100 mm) by having branchiae from chaetiger 22, while in M. brasiliensi s the branchiae start after chaetiger 31. Differences between M. viridis and M. acicularum were discussed in remarks of the latter.

Figures

FIGURE 1. Maxillary apparatus. A. Maxillae I, dorsal view; B. Maxillae II, left maxilla dorsal view, right maxilla ventral view; C. Maxillae III-V, dorsal view; D. Maxillae I-V, left maxillae lateral view. Mc, maxillary carriers; Cs, closing system (f, furrow; r, ridge, superscript number indicate the matching pair); Fa, falcal arch; Co cavity opening; L ligament between maxillae; al-MIII attachment lamella MIII, al-MIV attachment lamella MIV; dotted line in right MII showing the length of the cavity opening.

FIGURE 2. Marphysa acicularum Webster, 1884. Syntype USNM 4793. A. Anterior end, dorsal view; B. Maxillary apparatus; C. Parapodium 3, anterior view; D. Parapodium 9, anterior view; E. Parapodium 103, anterior view; F. Parapodium 219, anterior view. Scale bars: A, 2 mm, B, 1 mm; C, 153 µm; D: 163 µm; E, 300 µm; F, 213 µm.

FIGURE 3. Marphysa acicularum Webster, 1884. Syntype USNM 4793. A. Isodont pectinate chaetae, wide with short and fine teeth, anterior chaetiger; B. Anodont pectinate chaetae, wide with long and slender teeth, posterior chaetiger; C. Compound spiniger, chaetiger 103; D. Aciculae, median chaetiger (left acicula with distal end partially broken); E. Bidentate subacicular hook, median chaetiger; F. “ Unidentate ” subacicular hook, median chaetiger. Scale bars: A, 5 µm; B, 5.5 µm; C, 20 µm; D, 18 µm; E – F, 14 µm.

FIGURE 4. Marphysa nobilis Treadwell, 1917. A. Anterior end, dorsal view; B. Anterior end, dorsal view, live specimen; C. Anterior end, ventral view; D. Maxillary apparatus, dorsal view; E. Left MII-MV, dorsal view; F. Mandibles. A from holotype AMNH VI – 1915 – 1350; B – C from ECOSUR-OH-P 0128; D – F from ECOSUR-OH-P 0126. Scale bars: A, 1.5 mm; B – C: 2 mm; D – F, 1 mm.

FIGURE 7. Marphysa viridis Treadwell, 1917. A. Anterior end, dorsal view; B. Anterior end, ventral view; C. Maxillary apparatus, dorsal view; D. Left MI-MV, dorsal view; E. Mandibles. A – B from holotype AMNH VI – 1915 – 1293; C – E from ECOSUR-P 2677. Scale bars: A – E, 1 mm.

FIGURE 8. Marphysa viridis Treadwell, 1917. A. Parapodium 3, anterior view; B. Parapodium 14, anterior view; C. Parapodium 103, anterior view; D. Parapodium 167, anterior view; E. Parapodium 200, anterior view; F. Subacicular hook, distal end, chaetiger 155; G. Isodont pectinate chaetae, narrow with short and fine teeth, chaetiger 14; H. Isodont pectinate chaetae, wide with short and fine teeth, chaetiger 103; I. Anodont pectinate chaetae, wide with long and thick teeth, chaetiger 103; J. Compound spiniger, chaetiger 110. A, E – J from ECOSUR-P 2677; B – D from holotype AMNH VI – 1915 – 1293. Scale bars: A, 267 µm; B, 234 µm; C, 347 µm; D, 267 µm; E, 347 µm; F – G, 15 µm; H: 25 µm; I, 52 µm; J, 12 µm.

FIGURE 9. Length-dependent variation of some morphological features in Marphysa viridis Treadwell, 1917. A. Maximum number of branchial filaments (n = 22); B. Last chaetiger with well developed postchaetal lobe (DPL) (n = 33); C. Last chaetiger with ventral cirri with swollen base (VCSB) (n = 9); D. Start of subacicular hooks (n = 33).

FIGURE 10. Distribution of branchial filaments throughout the body in Marphysa acicularum Webster, 1884, M. nobilis Treadwell, 1917 and M. viridis Treadwell, 1917.