Marphysa baileybrockae, Molina-Acevedo & Idris, 2020

Molina-Acevedo, Isabel C. & Idris, Izwandy, 2020, Reinstatement of species belonging Marphysa sanguinea complex (Annelida Eunicidae) and description of new species from the mid-Pacific Ocean and the Adriatic Sea, Zootaxa 4816 (1), pp. 1-48 : 7-8

Marphysa baileybrockae n. sp.

Figures 2 , 9B , Table 1

Marphysa teretiuscula . — Treadwell 1906: 1172 (non Schmarda, 1861).

Marphysa sanguinea . — Abbott, 1946: 6.— Hartmann-Schröder 1965: 137.— Hartman 1966: 218 (non Montagu, 1813).

Examined material. Type material: Holotype USNM 5444 , paratype AMNH 367 (1 specimen), Honolulu Reef , Oahu Island , Hawaii, United States, North Pacific Ocean, Albatross, 1902, col. United States Fish Commission.

Description. Holotype complete, dorsally dissected, with 312 chaetigers, broken in two parts (first one with 137 chaetigers), L10 = 11.7 mm, W10 = 3.8 mm, TL = 151 mm. Last 16 chaetigers regenerating. Anterior region of the body with dorsum convex and flat ventrum; body depressed from chaetiger 11, widest at chaetiger 33, tapering after chaetiger 41.

Prostomium bilobed, 1.2 mm long, 2.5 mm wide; lobes frontally trucate; median sulcus shallow anteriorly and deep ventrally ( Fig. 2 A–B). Prostomial appendages in a semicircle, median antenna isolated by a gap. Palps reaching second peristomial ring; lateral antennae reaching first chaetiger; median antenna broken, reaching first chaetiger; in paratype median antenna reaching second chaetiger. Palpophores and ceratophores ring-tapering, short, slender; palpostyles and ceratostyles tapering, slender. Eyes rounded, brown, between palps, and lateral antennae.

Peristomium (1.9 mm long, 4 mm wide) larger than prostomium, first ring two times longer than second ring, separation between rings distinct on all sides ( Fig. 2 A–C). Ventral lip without central anterior depression ( Fig. 2B ).

Maxillary apparatus with MF = 1 + 1, 4 + 5, 7 + 0, 4 + 8, 1 + 1 ( Fig. 2D ). MI 2.4 times longer than length of maxillary carriers. MI forceps-like, MI 3.8 times longer than length of closing system ( Fig. 2 D–E); ligament between MI and MII sclerotized. MII with recurved triangular teeth; MII 4.8 times longer than length of cavity opening ( Fig. 2 D–E); ligament between MII and MIII and right MIV, sclerotized. MIII with rounded teeth; with irregular attachment lamella, situated in center of the right edge of the plate, sclerotized ( Fig. 2 D–E). Left MIV with three lateral teeth larger than rest; attachment lamella semicircle, slender, better developed in left side, situated 4/3 along anterior edge of the maxilla, sclerotized. Right MIV with teeth of similar size; attachment lamella semicircle, wide, better developed in left side, situated 4/3 along anterior edge of the maxilla, sclerotized ( Fig. 2 D–E). MV square with a short, rounded tooth. Mandibles dark; calcareous cutting plates present in left side, sclerotized cutting plates brown, with 16 growth rings ( Fig. 2F ).

Pectinate branchiae with up to three long filaments, present from chaetigers 30R–32L to 293 ( Fig. 2 K–J). First seven and last 20 chaetigers with one filament; reaching the maximum three filaments in chaetigers 54L to 215L ( Fig. 9B ). Branchiae with filaments longer than dorsal cirri.

First four parapodia smaller, best developed in chaetigers 5–34, following ones gradually smaller. Dorsal cirri conical in all chaetigers; longer than ventral cirri in anterior and posterior chaetigers, shorter in median chaetigers; best developed in chaetigers 1–16, following ones gradually smaller ( Fig. 2 G–K). Prechaetal lobes short, in the first 23 chaetiger with dorsal edge longer than ventral; following ones as a transverse fold in all chaetigers ( Fig. 2 G–K). Chaetal lobes rounded in first 22 chaetigers, shorter than postchaetal lobes, with aciculae emerging dorsal to midline; from chaetiger 23 triangular, longer than other lobes, with acicula emerging in midline ( Fig. 2 G–K)). Postchaetal lobes well developed in first 59 chaetigers; conical with distal edge directed to dorsal side in first five chaetigers, ovoid with dorsal edge longer than ventral in chaetigers 6 to 11, progressively smaller from chaetiger 13; from chaetiger 60 inconspicuous ( Fig. 2 G–K). Ventral cirri digitiform in first four chaetigers; from chaetigers 5 to 287 with an oval swollen base and digitiform tip; digitiform from chaetiger 288, gradually reducing in size ( Fig. 2 G–K).

Aciculae blunt, reddish along most of its length, and translucent on the distal tip in first 16 chaetigers; following aciculae translucent completely ( Fig. 2 G–K). First four chaetigers with two aciculae; in chaetigers 5–14 with three or four; in chaetigers 15–137 with four or five; in chaetigers 138–174 with four; in chaetigers 175–277 with three; in chaetigers 278–295 with two; from chaetiger 296 with two or one acicula.

Limbate chaetae of two length sizes in same chaetiger: long and short, long blades in dorsal position, short blades in ventral position; limbate chaetae reduced in number around chaetiger 19, and then maintained a similar number until the posterior end. Three types of pectinate chaetae; in most of chaetigers, thin, isodont narrow, symmetric, with short, and slender teeth, with 6–8 pectinate, with up to 20–22 teeth ( Fig. 2L ); in median-posterior chaetigers, thick, isodont wide, symmetric, with long, and slender teeth, with 1–2 pectinate, with up to 24 teeth ( Fig. 2N ), and thick, anodont wide, symmetric, with long and thick teeth, with 1–2 pectinate, with up to six teeth ( Fig. 2M ). Compound spinigers present throughout, with blades of two lengths in all chaetigers: shorter blades more abundant than longer blades ( Fig. 2O ). Subacicular hooks unidentate, translucent ( Fig. 2P ); starting from chaetiger 32, one or two per chaetiger (second replacement hook), present discontinuously after chaetigers 32; in posterior chaetigers hooks bidentate, with blunt teeth, distal tooth smaller than proximal, directed upward, proximal directed laterally ( Fig. 2Q ).

Pygidium with dorsal pair of anal cirri as long as last four chaetiger; ventral pair short, as long as last chaetiger.

Variation. Material examined with L10 = 4.8–11.7 mm, W10 = 2.3–3.8 mm, TChae = 182–312. Palps reaching second peristomial ring; lateral antennae reaching first or second chaetiger; median antenna reaching second chaetiger. Branchiae from chaetigers 22–30 to 19–20 chaetigers before pygidium. Maximum number of branchial filaments is three. Postchaetal lobe conspicuous in first 47–59 chaetigers. Ventral cirri with a swollen base from chaetigers 5–6 to 21–25 chaetigers before of pygidium. Start of subacicular hooks in chaetigers 27–32.

Type locality. Honolulu Reef , Hawaii .

Distribution. Honolulu, Kaneohe Bay, Hawaii.

Habitat. According to Treadwell (1906), the material was collected from Honolulu reef. Hartmann-Schröder (1965) studied three specimens from Oahu, Kaneohe Bay, collected from coral sand.

Etymology. The species is named after Dr. Julie H. Bailey-Brock, in recognition of her valuable contributions to the taxonomic study of the polychaete from Hawaii.

Remarks. Treadwell (1906) identified two specimens collected from Honolulu as M. teretiuscula , a species described by Schmarda (1861) from Sri Lanka. Later, Abbott (1946) and Hartmann-Schröder (1965) reported specimens with similar features to Treadwell’s specimens but identified them as M. sanguinea from Kaneohe Bay, Hawaii. Then, Hartman (1966) reviewed the species studied by Treadwell and concluded that the material previously identified as M. teretuiscula belongs to M. sanguinea .

Treadwell (1906) only indicated a small difference in the number of branchial filaments from Schmarda’s original description; however, after a detailed comparison between the type material of M. teretiuscula , M. sanguinea and Treadwell’s specimens, herein some significant differences were found. Hence, the specimens from Honolulu are considered as a new species, Marphysa baileybrockae n. sp..

Marphysa baileybrockae n. sp. (type material L10 = 4.8–11.7 mm) has branchiae from chaetigers 22 to 30 with up to three branchial filaments, whereas M. teretiuscula (type and additional material, L10 = 5.5–12.4 mm) has branchiae from the chaetigers 18 to 32 with up to four to six branchial filaments. Furthermore, in M. baileybrockae n. sp. the postchaetal lobe is conical in anterior chaetigers, the ventral cirri with a swollen base end 21–25 chaetigers before of pygidium, and the subacicular hook is translucent, instead of M. teretiuscula in which the postchaetal lobe is ovoid in anterior chaetigers, the ventral cirri with a swollen base end 34–68 chaetigers before pygidium, and the subacicular hook is reddish in most of its length and translucent distally.

M. baileybrockae n. sp. is different from M. sanguinea (type and additional material L10 = 11.5–20.4 mm) by the color translucent of the subacicular hook, whereas in M. sanguinea the subacicular hook is reddish on the base and translucent in distal end. Furthermore, the new species only has up to three branchial filaments, and the distal edge of the postchaetal lobe is directed to dorsal side, instead of M. sanguinea that has up to five or six branchial filaments, and the distal edge is straight. Also, M. baileybrockae n. sp. has only one or two thick isodont wide pectinate, with long and slender teeth in median and posterior chaetigers, whereas in M. sanguinea there are 18–20 pectinate chaetae in the same region or the body.

Marphysa baileybrockae n. sp. resembles M. acicularum ( Bermuda) , M. brasiliensis ( Hansen, 1882) ( Brazil) , M. bulla (Yellow Sea, China), M. californica (California) , M. maxidenticulata (Yellow Sea, China), and M. parishii ( Brazil) by having the pectinate branchiae with long branchial filaments, absence of subacicular limbate chaetae, subacicular hook translucent, and the dorsal cirri conical in all chaetigers. Nonetheless, M. baileybrockae n. sp. has three types of pectinate chaetae throughout the body, whereas M. bulla and M. parishii have five types, and M. californica and M. maxidenticulata have four types of pectinate chaetae. Moreover, M. baileybrockae n. sp. has the prechaetal lobe in first chaetigers with dorsal edge longer than ventral, in contrast of M. brasiliensis , M. bulla , M. californica , M. maxidenticulata , and M. parishii that the prechaetal lobe is as a transversal lobe. Furthermore, M. baileybrockae n. sp. has the postchaetal lobe directed to dorsal side, instaed of M. acicularum , M. brasiliensis , M. bulla , M. californica , M. maxidenticulata , and M. parishii which the postchaetal lobe is straight. The comparison of M. baileybrockae n. sp. with related species is provided in Table 1.

Figures

FIGURE 2. Marphysa baileybrockae n. sp. A. Anterior end, dorsal view; B. Anterior end, ventral view; C. Anterior end, lateral view; D. Maxillary apparatus, dorsal view; E. Left MI-II-III-IV-V, lateral view; F. Mandible; G. Parapodium 3; H. Parapodium 8; I. Parapodium 16; J. Parapodium 250; K. Parapodium 308; L. Thin, isodont narrow, symmetric, with short and slender teeth, chaetiger 8; M. Thick, anodont wide, symmetric, with long and thick teeth, chaetiger 295; N. Thick, isodont wide, symmetric, with long and slender teeth, chaetiger 358; O. Compound spinigers, chaetiger 8; P. Subacicular hook unidentate, chaetiger 122; Q. Subacicular hook bidentate, chaetiger 152. A–O from holotype USNM 5444, P–Q from paratype AMNH 367. All chaetigers in anterior view; al-MIII: attachment lamella MIII; al-MIV: attachment lamella MIV. Scale bars: A–C, 2.9 mm; D–E, 1 mm; F, 0.8 mm; G–K, 0.1 mm; L–Q, 30 µm.

FIGURE 9. Distribution of branchial filaments throughout the body in A. Marphysa americana Monro, 1933 n. status.; B. Marphysa baileybrockae n. sp.; C. Marphysa birgeri n. sp.; D. Marphysa brevibranchiata Treadwell, 1921 n. status.; E. Marphysa californica (Moore, 1909); F. Marphysa leidii de Quatrefages, 1866; G. Marphysa parishii Baird, 1869; H. Marphysa sanguinea (Montagu, 1813).