Marphysa teretiuscula (Schmarda, 1861a)

Molina-Acevedo, Isabel Cristina & Idris, Izwandy, 2021, Unravelling the convoluted nomenclature of Marphysa simplex (Annelida, Eunicidae) with the proposal of a new name and the re-description of species, Zoosystematics and Evolution 97 (1), pp. 121-139 : 121

Marphysa teretiuscula (Schmarda, 1861a) Figures 5 , 6 , 7 , 8 , 9 , Table 2

Eunice teretiuscula Schmarda, 1861a: 129, pl. 32, fig. 59, text-figs a-d, f, OK, UK; Grube 1878: 59.

Marphysa teretiuscula - de Quatrefages 1866: 337; Ehlers 1868: 359; Crossland 1903: 136; - Hartman 1959: 332; - Glasby and Hutchings 2010: 32, 40-41, table 2; Liu et al. 2017: 244-247, table 3; - Liu et al. 2018: 210-211, table 1.

Marphysa simplex Crossland, 1903: 140-141, pl. 15, figs. 11-12, text-fig. 13.

Material examined.

Eunice teretiuscula Schmarda, 1861a

Sri Lanka · two specimens, one of them missing anterior end; Trincomalee, east of Sri Lanka; May 1853 to Jan 1854; L.K. Schmarda leg.; syntypes NHMW type 1092.

Marphysa simplex Crossland, 1903

Zanzibar · two adult specimens; 11 Jan 1934; Murray Exped. St. 104, Petersen Grab, V.310, 207 m; syntypes BNHM type 1937.9.2.325.

Other material.

Marphysa teretiuscula (Schmarda, 1861a)

Mozambique · two specimens; Morrumbene Estuary; 16 Jan 1954; BNHM 1955.4.1.21-25.

India · one specimen; Ratnagiri Creek, Shirgaon, Maharashtra; 17°17'13.78"N, 73°17'13.87"E; 18 Apr 1994; USNM 1128572 · one specimen; same data as for preceding; USNM 1128570.

Comparative material examined.

Marphysa furcellata Crossland, 1903

Zanzibar · two specimens; 1901; between tidemarks, 27.4 m; C. Crossland leg.; syntypes BNHM 1924.3.1.139.

Marphysa macintoshi Crossland, 1903

Zanzibar · three specimens; 1901-1902; collected by digging in sand between tidemarks on both east and west coast of Zanzibar; syntypes BNHM 1924.3.1.22-3, slide BNHM.1924.3.1.22A.

Description.

Syntype NHM type 1092 incomplete, gravid female, with 210 chaetigers, L10 = 9.3 mm, W10 = 5 mm TL = 860 mm (Fig. 5A-C ). Anterior region with dorsum convex, flat ventre (Fig. 5C, E ); body depressed from chaetiger 13 (Fig. 5C, E ), widest at chaetiger 51, tapering after chaetiger 173.

Prostomium bilobed, 4 mm long, 2.5 mm wide; lobes frontally rounded; median sulcus (Fig. 5A, B, D ) shallow and deep ventrally. Prostomial appendages in semicircle, median antenna isolated by a gap. Palps reaching second chaetiger; lateral antennae reaching middle of third chaetiger; median antennae reaching fourth chaetiger. Palpophores and ceratophores ring-shaped, short, thick; palpostyles and ceratostyles tapering, slender. On right side with two palpostyle in the same palpophore (Fig. 5C ). Eyes oval, brown, between palps and lateral antennae.

Peristomium (2 mm long, 5.2 mm wide) wider than prostomium, first ring twice as long as second ring, separation between rings distinct on all sides (Fig. 5A-E ). Ventral lip with slight central depression, with several shallow wrinkles (Fig. 5B ).

Maxillary apparatus with MF = 1+1, 4+4, 5+0, 5+7, 1+1 (Fig. 5H ). MI three times longer than length of maxillary carriers. MI forceps-like, MI four times longer than closing system (Fig. 5H, I ); sclerotised ligament between MI and MII. MII wider than rest of maxillae, with triangular teeth; MII 3.2 times longer than cavity opening (Fig. 5H ); ligament between left MII-MIII and right MII-MIV, slightly sclerotised. MIII with triangular teeth; with irregular attachment lamella, situated in centre of ventral edge of maxilla, slightly sclerotised (Fig. 5I ). Left MIV with two teeth larger than rest of teeth; attachment lamella semicircle, wide, better developed in right portion, situated 2/3 along anterior edge of maxilla (Fig. 5J ). Right MIV with four teeth larger than rest of teeth; attachment lamella semicircle, wide, better developed in central portion, situated 2/3 along anterior edge of maxilla (Fig. 5K ). MV square, with a short triangular tooth. Mandibles dark; with calcareous cutting plates; sclerotised cutting plates brown, with nine growth rings (Fig. 5L ).

Branchiae from chaetiger 32, with up to five long filaments; with two forms: palmate with short button-shaped branchial stem in anterior chaetigers (Fig. 6F, H ), pectinate in median chaetigers (Fig. 6G ). In second syntype, branchiae ending 25 chaetigers before pygidium. One filament in chaetigers 32L-34L; 2 in chaetigers 35L-39L; 3 in chaetigers 40L-48L; 3, 4 or 5 from chaetiger 49L to last chaetiger of the fragment. In second syntype, last 18 branchiae with one filament. Branchial filaments longer than dorsal cirri.

First pair of parapodia small; best developed in chaetigers 11-56, following parapodia gradually decreasing in size. Dorsal cirri conical in all chaetigers; longer than ventral cirri in anterior and posterior chaetigers, shorter in median chaetigers; best developed in chaetigers 3-37, following gradually decreasing in size (Fig. 6A-K ). Prechaetal lobes short, in anterior chaetigers dorsal edge longer than ventral, in median-posterior chaetigers, as transverse fold (Fig. 6A-K ). Chaetal lobes rounded in first 35 chaetigers, shorter than other lobes, with aciculae emerging dorsal to mid-line; triangular from chaetiger 36, longer than other lobes, with aciculae emerging in mid-line (Fig. 6A-K ). Postchaetal lobes well developed in first 56 chaetigers; ovoid with dorsal edge longer than ventral edge in following chaetigers; progressively smaller from chaetiger 19; from chaetiger 57, inconspicuous (Fig. 6A-K ). Ventral cirri conical in first five chaetigers; from chaetiger 6 to last chaetiger of fragment with short oval swollen base and digitiform tip (Fig. 6A-K ). Second syntype with ventral cirri with short oval swollen base and digitiform tip up to 27 chaetigers before pygidium; digitiform in following ones, gradually decreasing in size posteriorly.

Aciculae blunt, basally reddish and translucent distally (Fig. 6A-K ). First two chaetigers with two aciculae; in chaetigers 3-5 with three or four; in chaetigers 6-47 with four or five; in chaetigers 48-139 with three; from chaetiger 140, with two. In second syntype, last 20 chaetigers with one acicula.

Limbate chaetae of two lengths in same chaetiger, dorsalmost chaetae longer; reduced in number around chaetiger 13. Three types of pectinate chaetae; from chaetiger 11 thin, isodont narrow chaetae, with short and slender teeth; in anterior chaetigers with 1-2 pectinate and with up to 21-22 teeth; in median-posterior chaetigers, with 20-25 pectinate and 30-32 teeth (Fig. 7A, B ). In median-posterior chaetigers, 3-4 thick, isodont wide chaetae, with up to 16-18 long and wide teeth (Fig. 7C ). In posterior chaetigers, 2-3 thick, anodont wide chaetae, with up to 6-7 long and thick teeth (Fig. 7D ). Compound spinigers present in all chaetigers, with blades of two lengths in the same chaetiger, shorter ones more abundant (Fig. 7E, F, G ). Subacicular hooks present from chaetiger 33 to 140, with continuous distribution, one or two per chaetiger (second one replacement); unidentate in anterior chaetigers (Fig. 7H ), bidentate in median chaetigers, basally reddish translucent distally; with blunt teeth, distal and proximal teeth of similar sizes, booth teeth directed upwards (Fig. 7I ).

In second syntype, pygidium with dorsal pairs of anal cirri, as long as last 12 chaetigers; ventral pair of anal cirri short, as long as last three chaetigers (Fig. 5G ).

Variation.

Material examined varied in the following features: L10 = 3.1-12.4 mm, W10 = 0.8-5 mm, TChae = 88-265. Palps reaching middle of first peristomial ring or first chaetiger; lateral antennae reaching first or middle of first chaetiger; median antenna reaching middle of first or second chaetiger. Maxillary formula: MII 4-6+4-7, MIII 5-8, MIV 4-5+7-9. MI is 3-3.1 × longer than maxillary carriers; MI is 4.4-5.5 × longer than closing system; MII is 2.7-3.4 × longer than cavity opening. Branchiae starting from chaetigers 15-32 and disappearing 7-12 chaetigers before pygidium. The maximum number of branchial filaments varies from two to six. Postchaetal lobes well developed in first 20-56 chaetigers. Ventral cirri with swollen base starting from chaetigers 4-8 and disappearing 34-68 chaetigers before pygidium. Start of subacicular hooks from chaetigers 23-38.

Regression analyses showed a correlation between L10/W10 and the first branchiate chaetiger (R² = 0.7328, p = 1.65708E-05, n = 7, Fig. 8A ), the last chaetiger with developed postchaetal lobe (R² = 0.7976, p = 0.00028646, n = 7, Fig. 8B ) and the first chaetiger with subacicular hook (R² = 0.6291, p = 2.02774E-07, n = 7, Fig. 8C ). Most of the specimens were incomplete and regression analysis regarding the maximum number of branchial filaments in the body could not be performed.

Distribution.

Sri Lanka, Maharashtra (India), Zanzibar.

Habitat.

Unknown. Schmarda (1861a) did not indicate the habitat of the species.

Remarks.

Schmarda (1861a) collected M. teretiuscula (firstly in the genus Eunice ) in the east of Ceylon (now Sri Lanka) during a series of expeditions around the world to collect fauna and flora ( Schmarda 1859; Villalobos-Guerrero 2019). The syntypes label only states ‘Trincomalie’ (Trincomalee) as the collecting site, but no collecting date is given. However, the expedition notes ( Schmarda 1861b) state that he visited Ceylon from May 1853 to January 1854, whereby, based on this information, the syntypes of M. teretiuscula were most likely collected during this time.

Crossland (1903) described M. macintoshi , M. simplex and M. furcellata from Zanzibar. These species were differentiated, based on the shape of the prostomium and the pectinate chaetae. However, some authors considered these features irrelevant over time and proposed several synonyms between them or other species from distant regions. For instance, Fauvel (1919) considered M. furcellata to be a junior synonym of M. sanguinea Montagu, 1813. On the contrary, Day (1957) indicated that M. sanguinea differed from M. furcellata by having bidentate subacicular hooks, whereas, in the latter species, they are unidentate. However, Day regarded M. furcellata as a junior synonym of M. simplex (Crossland). Later, Day (1962) pointed out that M. furcellata and M. simplex (Crossland) were synonyms of M. macintoshi , considering that the prostomium’s shape was insufficient to differentiate them. More recently, Glasby and Hutchings (2010) recognised that an entire prostomium is useful to distinguish M. macintoshi from M. furcellata and M. simplex (Crossland). Simultaneously, Glasby and Hutchings (2010) compared M. simplex (Crossland) and M. teretiuscula , but they also did not detect morphological differences between them. After examining the type materials, we confirm the validity of Crossland’s species M. macintoshi and M. furcellata and the synonymy of M. simplex (Crossland) with M. teretiuscula (see Figs 5 - 7 ).

Marphysa teretiuscula resembles M. borradailei Pillai, 1958 from Sri Lanka and the Indian Ocean, M. furcellata from Zanzibar, M. gravelyi Southern, 1921 from Chilka Lake, India, M. macintoshi from Zanzibar and M. madrasi Hutchings, Lavesque, Priscilla, Daffe, Malathi & Glasby, 2020 from Ennore Creek, India by having compound spinigers and inhabiting the same geographical area. However, M. teretiuscula bears only subacicular chaetae compound spinigers, while M. borradailei , M. gravelyi and M. madrasi have both subacicular spinigers and limbate chaetae. Furthermore, M. teretiuscula has distinct bilobed prostomium, in contrast to an entire prostomium in M. macintoshi . Moreover, M. teretiuscula has palmate branchiae with a short button-shaped branchial stem in the anterior region, the postchaetal lobe is rounded in the first three chaetigers and the subacicular hooks are reddish basally and translucent distally. In contrast, M. furcellata has pectinate branchiae in the anterior region, digitiform postchaetal lobes in the first chaetigers and translucent subacicular hooks. In addition, M. teretiuscula , M. furcellata and M. macintoshi differ by distributing the branchial filaments throughout the body. In M. teretiuscula , the maximum number of five branchial filaments is present only in a small/low number of chaetigers (between chaetiger 86 and 106), while in M. furcellata and M. macintoshi , the maximum number of five branchial filaments (in each species) is found in a larger number of chaetigers (in M. furcellata from chaetiger 80 to 120+ and in M. macintoshi from chaetiger 105 to 236; Fig. 9 ).

Marphysa teretiuscula resembles M. americana Monro, 1933, M. angelensis Fauchald, 1970, M. depressa (Schmarda, 1861a), M. emiliae Molina-Acevedo and Carrera-Parra, 2017, M. nobilis Treadwell, 1917, M. sanguinea (Montagu, 1913) and M. tripectinata Liu, Hutchings & Sun, 2017 in having reddish subacicular hooks, the presence of compound spinigers and the absence of subacicular limbate chaetae. However, M. teretiuscula has palmate branchiae with a short bottom-stem in the anterior region, contrary to M. americana , M. angelensis , M. depressa , M. emiliae , M. nobilis and M. sanguinea which have pectinate branchiae throughout the body. Furthermore, M. teretiuscula has compound spinigers in all chaetigers, while in M. depressa , the spinigers are restricted to the anterior region. In addition, M. teretiuscula has the postchaetal lobe rounded in the first three chaetigers, while it is conical in the first three parapodia of M. americana and digitiform in M. angelensis , M. depressa , M. emiliae and M. sanguinea . Moreover, M. teretiuscula has distinctly longer branchial filaments than in M. angelensis . Additionally, M. teretiuscula has the subacicular hook as wide as the acicula, in contrast to that half as wide as acicula in M. nobilis and M. tripectinata . The comparison of M. teretiuscula with similar species is provided in Table 2 .

Figures

Figure 5. Marphysa teretiuscula (Schmarda, 1861 a). A. Anterior end, dorsal view; B. Anterior end, ventral view; C. Anterior end, lateral view; D. Anterior end, dorsal view; E. Anterior end, lateral view; F. Median region, ventral view; G. Pygidium, dorsal view; H. Maxillary apparatus, dorsal view; I. Left MI-II-III-IV-V, lateral view; J. Attachment lamella in left side, dorsal view; K. Attachment lamella in right side, lateral view; L. Mandible, ventral view. A-C, H-L. from M. teretiuscula (Schmarda, 1861) syntype 1 (NHMW type 1092); D-G. from Marphysa simplex Crossland, 1903 syntype 1 (BNHM 1955.4.1.21 - 25). al-MIII: attachment lamella MIII; al-MIV: attachment lamella MIV; al-MIV-L: attachment lamella MIV on left side; al-MIV-R: attachment lamella MIV on right side; MI-R: Maxilla I on right side; MII-R: Maxilla II on right side. Scale bars: 2.3 mm (A-C); 3.1 mm (D-F); 1.16 mm (G); 3.0 mm (H, I, L); 1.13 mm (J); 0.9 mm (K).

Figure 6. Marphysa teretiuscula (Schmarda, 1861 a). A, B. Chaetiger 3; C. Chaetiger 7; D. Chaetiger 12; E. Chaetiger 14; F. Chaetiger 47; G. Chaetiger 97; H. Chaetiger 143; I. Chaetiger 162; J. Chaetiger 44 before pygidium; K. Chaetiger 256. All chaetigers in anterior view. A, D, F, H. from M. teretiuscula (Schmarda, 1861 a) syntype 1 (NHMW type 1092); J. from M. teretiuscula (Schmarda, 1861 a) syntype 2 (NHMW type 1092); B, C, E, G, I, K. from Marphysa simplex Crossland, 1903 syntype 1 (BNHM 1955.4.1.21 - 25). Arrows in F, H. indicate the button-shaped branchial stem. Scale bars: 0.2 mm (A, D, F, H, J); 0.1 mm (B, C, E, G, I, K).

Figure 7. Marphysa teretiuscula (Schmarda, 1861 a). A. Thin, isodont narrow pectinate, with short and slender teeth, chaetiger 47; B. Thin, isodont narrow pectinate, with short and slender teeth, chaetiger 189; C. Thick, isodont wide, with long and wide teeth, chaetiger 44 before pygidium; D. Thick, anodont wide, with long and wide teeth, chaetiger 256; E. Compound spinigers, chaetiger 44 before pygidium; F. Compound spiniger, chaetiger 211; G. Compound spinigers, chaetiger 47; H. Unidentate subacicular hook, chaetiger 47; I. Bidentate subacicular hook, chaetiger 73 before pygidium. A, B. from M. teretiuscula (Schmarda, 1861 a) syntype 1 (NHMW type 1092); C, E, I. from M. teretiuscula (Schmarda, 1861 a) syntype 2 (NHMW type 1092); D, F. from Marphysa simplex Crossland, 1903 syntype 1 (BNHM 1955.4.1.21 - 25); G, H. from M. simplex Crossland, 1903 syntype 2 (BNHM 1955.4.1.21 - 25). Scale bars: 20 μm (A-D, G); 60 μm (E); 50 μm (F, H, I).

Figure 8. Large chaetiger 10 (L 10) / Wide chaetiger 10 (W 10) - dependent variation of some morphological features in Marphysa teretiuscula (Schmarda, 1861 a). A. First chaetiger where the branchiae start (R ² = 0.7328, p = 1.65708 E- 05, n = 7); B. Last chaetiger where the postchaetal lobe is developed (R ² = 0.7976, p = 0.00028646, n = 7); C. Chaetiger where the subacicular hook starts (R ² = 0.6291, p = 2.02774 E- 07, n = 7).

Figure 9. Distribution of branchial filaments throughout the body. A. Syntype 1 of Marphysa simplex Crossland, 1903 (BNHM 1924.3.1.1 - 2) with L 10: 8.6 mm, TL: 137 mm and 273 chaetigers; B. Syntype 1 of Marphysa furcellata Crossland, 1903 (BNHM 1924.3.1.139) with L 10: 6.3 mm, TL: 40 mm and 114 chaetigers; C. Syntype 1 of Marphysa macintoshi Crossland, 1903 (BNHM 1924.3.1.22 - 3) with L 10: 8.1 mm, TL: 18.8 mm and 262 chaetigers. Dotted blue line in B indicates the organism is incomplete.