Marphysa kertehensis, Che Engku Abdullah & Idris & Fahmi & Flaxman & Hutchings, 2024

Che Engku Abdullah, Che Engku Siti Mariam, Idris, Izwandy, Fahmi, Afiq Durrani Mohd, Flaxman, Beth & Hutchings, Pat, 2024, Four new species of Marphysa (Annelida, Eunicida, Eunicidae) from the east coast of Peninsular Malaysia, ZooKeys 1204, pp. 65-103 : 65-103

Marphysa kertehensis sp. nov.

Figs 1 , 2 , 5 , 6 , 7

Material examined.

Holotype. UMTAnn 2181 , complete (regenerated posterior), antero-ventrally dissected, some parapodia removed and mounted for SEM . Paratypes. AM W. 54059 , complete, some parapodia removed and mounted for SEM; LACM-AHF 13503 to 13505, complete, some parapodia removed; ZRC. ANN. 1614 to 1615, incomplete, some parapodia removed; SAM-MB-A 096023, incomplete, some parapodia removed . All material was collected from the east coast of Peninsular Malaysia, Terengganu, Kerteh mangrove forest river (04 ° 32.142 ' N, 103 ° 26.363 ' E), March 2022.

Diagnosis.

Prostomium completely bilobed, five prostomial appendages without articulations; eyes absent. Peristomium without peristomial cirri. Maxillary apparatus with four pairs of maxillae, an unpaired one on the left side, MI with falcal arch extended at sub-right angle, basal outer edge arched, basal inner edge lacking curvature. MII with triangular teeth and without attachment lamella. MIII slightly curved, with equal-sized triangular teeth, without attachment lamella. MIV with dark and curved attachment lamella. Branchiae distributed along entire body. Dorsal cirri without articulations; postchaetal lobe well developed in anterior regions. Ventral cirri with swollen, inflated base. Sub-aciculae black, blunt and translucent at distal end, pale brown in posterior-most parapodia. Supra-acicular chaetae include limbate, pectinate thin, narrow and wide isodont with short and slender inner teeth, and pectinate thick, wide isodont with short and slender inner teeth. Subacicular chaetae include only limbate chaetae. Subacicular hook absent. Pygidium with two pairs of anal cirri, without articulation.

Description

(based on holotype, with variation in parentheses for paratypes). Preserved specimens beige (Fig. 5 A ), with 518 (135–578) chaetigers, ~ 413 mm (173–295) total length, 12 mm (6–10.8) in length to chaetiger 10 (L 10), 4.8 mm (3.15–5.1 mm) width at chaetiger 10 (W 10), excluding parapodia. Body with dorsum convex and flat ventrum (Fig. 5 A ), without groove; body elongated, rounded in cross-section at anterior and median regions, and dorsoventrally flattened thereafter. Live specimens red (Fig. 7 D ).

Prostomium bilobed, anteriorly rounded with two dorsoventrally flattened lobes separated by an anterior notch between (Fig. 5 B ). Prostomial appendages in a semicircle, median antennae separated by a gap (Fig. 5 B ). Palps reach to first ring of peristomium; lateral and median antennae to second ring of peristomium. Palpophores and ceratophores are ring-shaped, short, thin; palpostyles and ceratostyles tapering and slender. Prostomial peduncles absent. Peristomium larger and wider than prostomium; first ring 3 × longer than second ring, separation between rings distinct on all sides.

Maxillae dark (Fig. 5 C ), and maxillary formula (MF) as follows: 1 + 1, 5 + 5 (4–5), 8 (7–8) + 0, 3 (3–4) + 9 (8–9), 1 + 1. Maxillary carrier ~ 2.8 × shorter than MI, rectangular anteriorly, triangular posteriorly. MI forceps-like, without attachment lamellae, falcal arch extended at sub-right angle, basal outer edge arched, basal inner edge lacking a curvature. Closing system ~ 4.2 × shorter than MI. Ligament between MI and MII dark. MII without attachment lamella, teeth triangular, distributed on <1 / 2 of plate length. Ligament between MII and MIII dark. MIII single, longer than left MIV, slightly curved, with equal-sized triangular teeth, without attachment lamella. Left MIV short (<1 / 2 the size of right MIV), attachment lamella dark, curved. Right MIV long, with teeth triangular, decreasing in size and teeth curved posteriorly; attachment lamella curved, dark. MV paired, longer than high. Mandible dark, longer than MI; cutting plates whitish (Fig. 5 D ).

First and second parapodia located ventrolaterally but gradually positioned dorsolaterally on subsequent segments. Chaetal lobes conical and directed to ventral cirri in anterior chaetigers, conical in median and posterior chaetigers (Fig. 5 E – G ). Prechaetal lobe shorter than chaetal lobe throughout body. Postchaetal lobe rounded and longer than chaetal lobe in anterior chaetigers, conical in mid-body onwards and absent in the posterior-most chaetigers. Dorsal cirri digitiform with slender and tapering tips longer than ventral cirri anteriorly, digitiform and slightly longer from mid-body, digitiform and approximately similar length in posterior-most chaetigers (Fig. 5 E – G ). Ventral cirri digitiform in first chaetigers, basally inflated with digitiform tip from chaetiger 15 onwards (Fig. 5 E – G ). Branchiae pectinate, from chaetiger 41 (27–58), branchial filaments 3 × longer than dorsal cirri where best developed; number of filaments increasing from five anteriorly to nine in mid-body, decreasing to three in last several chaetigers. Black dot present at the base of dorsal cirri from median chaetigers toward posterior chaetigers (Fig. 5 F – H ).

Notoaciculae absent, neuroaciculae black, blunt, and translucent at distal end along most of body, pale brown in posterior-most parapodia; three or four per parapodium in anterior, one or two per parapodium in median and posterior chaetigers (Fig. 5 E – G ). Supra-acicular chaetae with limbate capillaries and pectinates, subacicular chaetae with limbate capillaries, compound chaetae absent (Fig. 6 A, B ). Three types of pectinate chaetae were identified (types 1, 2, 4; see Fig. 2 ): type 1: thin, narrow isodont with 28 short and slender inner teeth, outer teeth longer on one side, present only in the anterior body region (Fig. 6 C ); type 2: thin, wide isodont with ~ 30–32 short and slender teeth, present only in median and posterior region (Fig. 6 C, D ); type 4: thick, wide isodont with ~ 23 short and slender inner teeth, present only in posterior region (Fig. 6 E, F ). Anodont pectinate chaetae and subacicular hooks (n = 30) completely absent. Pygidium with crenulated margin, with two pairs of pygidial cirri attached (Fig. 5 I ).

Etymology.

The new name denotes the type locality (Kerteh River) where the specimens were collected.

Type locality.

South China Sea, Malaysia, east coast of Peninsular, Terengganu, Kerteh River (see Fig. 1 ).

Distribution.

Known only from the type locality.

Habitat.

Gravelly muddy sand (Table 4 ), burrowing inside driftwood, in mangroves, intertidal (Fig. 7 A – C ) with salinity 3.18 ‰ during spring low tide.

Remarks.

With the presence of only limbate chaetae in both supra- and subacicular chaetae bundles, Marphysa kertehensis sp. nov. belongs to Marphysa Group A (Mossambica). Comparing Marphysa Group A from Malaysia’s coastal water bodies, M. kertehensis sp. nov. is similar to M. moribidii (type locality: Morib, Malaysia) in lacking eyes. Table 5 lists the characteristics of Group A species, such as the presence or absence of peduncle in the prostomial appendages, the number of types of pectinate chaetae, chaetiger from where the branchiae commence and finish, number of branchial filaments and subacicular hooks and all differ from the new species. Marphysa kertehensis sp. nov. has three types of pectinate chaetae (types 1, 2, 4) but lacks any wide anodont chaetae (types 6, 7, 8), while M. moribidii has four types, including wide anodont (types 1, 4, 5, 8). Although they all have the same type of pectinate branchiae and the chaetiger where the branchiae emerge, M. moribidii (TL: 333 mm) has a wider range variation of chaetiger where the branchiae emerge; they occur from chaetiger 35 (4–63) whereas in M. kertehensis sp. nov. (TL: 413 (173–295) mm), the branchiae are present from chaetiger 41 (27–58). There are no subacicular hooks present in all specimens of M. kertehensis sp. nov., but there are a few subacicular hooks present in the paratype of M. moribidii AM W. 38690. Additionally, M. kertehensis sp. nov. has a black dot at the base of dorsal cirri in median and posterior chaetigers, possibly a reservoir of blood to irrigate the branchiae, which is absent in M. moribidii . It is worth mentioning that comparisons between the two species were based only on morphological features as there is no sequence data published for M. moribidii . Furthermore, each species lives in a different habitat. Marphysa kertehensis sp. nov. was found in the driftwood within the mangrove area dominated by Exoecaria agallocha , meanwhile M. moribidii inhabits mangrove forest with Rhizophora spp. , Avicennia alba and Sonneratia caseolaris ( Idris et al. 2014) .

Figures

Figure 1. Map showing sampling sites of four new Marphysa species in Terengganu mangrove forest, east coast of Peninsular Malaysia A location of Terengganu on the east of Peninsular Malaysia B symbols indicate each sampling site; Setiu Wetlands (red star), Kuala Ibai (red rhombus), Merchang (red triangle), and Kerteh (red oval).

Figure 2. The schematic drawing of type of pectinate chaetae present in Marphysa from Terengganu A thin, narrow isodont with short and slender inner teeth (type 1) B thin, wide isodont with short and slender inner teeth (type 2) C thin, narrow heterodont with short and slender inner teeth (type 3) D thick, wide isodont with short and slender inner teeth (type 4) E thick, wide isodont with short and slender inner teeth (type 5) F thick, narrow anodont with long and thick inner teeth (type 6) G thick, wide anodont with long and slender inner teeth (type 7) H thick, wide anodont with long and thick inner teeth (type 8). Scale bars: 18 µm (A); 35 µm (B, G); 20 µm (C); 38 µm (D); 32 µm (E); 13 µm (F); 30 µm (H).

Figure 5. Marphysa kertehensis sp. nov. Holotype UMTAnn 2181 (A – I). Light microscopy images and digital drawing A anterior end, lateral view B anterior end, dorsal view C maxillae, dorsal view D mandibles, dorsal view E parapodium, chaetiger 10 F parapodium, chaetiger 295 G parapodium, chaetiger 462 H median region, dorsal view. Arrows indicate black dot at the base of dorsal cirri I posterior segments and pygidium, ventral view. Abbreviations; MI – MV: maxillae I – V, Ac: aciculae, Dc: dorsal cirrus, Vc: ventral cirrus, PCl: prechaetal lobe, Cl: chaetal lobe, PtCl: postchaetal lobe, Bf: branchial filament. Scale bars: 2 mm (A, H, I); 1 mm (B – D); 0.1 mm (E – G).

Figure 6. Scanning Electron Microscopy (SEM) images of Marphysa kertehensis sp. nov. Holotype UMTAnn 2181 (B – E), paratype AM W. 54059 (A, F) A limbate chaetae, chaetiger 10 B parapodia, chaetiger 300 C – D pectinate chaetae, chaetiger 300 E pectinate chaetae, chaetiger 462 F pectinate chaetae, chaetiger 525. Numbers denoted by arrows indicate the type of pectinate chaetae: 1. Thin, narrow isodont; 2. Thin, wide isodont; 4. Thick, wide isodont. Scale bars: 50 µm (A); 100 µm (B); 20 µm (C – D); 10 µm (E – F).

Figure 7. Sampling site in Kerteh mangrove forest (river area) A habitat of Marphysa kertehensis sp. nov. B Marphysa kertehensis sp. nov. found inside driftwood and C in the sediment D live and complete M. kertehensis sp. nov.