Marphysa aegypti, Elgetany & El-Ghobashy & Ghoneim & Struck, 2018

Elgetany, Asmaa H., El-Ghobashy, Ahmed E., Ghoneim, Ahmed M. & Struck, Torsten H., 2018, Description of a new species of the genus Marphysa (Eunicidae), Marphysa aegypti sp. n., based on molecular and morphological evidence, Invertebrate Zoology 15 (1), pp. 71-84 : 76-82

Marphysa aegypti sp.n.

Figs 2–3 .

M. sanguinea — Dorgham et al., 2014: 639.

TYPES. Holotype: Al ferdan of the Suez Canal ( Egypt) N 30°40′12.4″ / E 32°20′06.8″ ( NHMO C6963 ) . Paratypes: two specimens from Eladabia, Gulf of Suez (part of the Red Sea) N 29°56′06.0″ / E 32°28′36.6″ and one specimen from off the coast of Alexandria (Mediterranean Sea) N 31°12′43.0″ / E 29°53′02.4″ ( NHMO C6964 to C6966 ) .

MEASUREMENTS. Holotype complete specimen with 293 chaetigers, about 143 mm long and about 6 mm wide (without parapodia) at chaetiger 10; 9 mm wide (without parapodia) at widest region (chaetigers 35–205). Length of postchaetal lobe in anterior most and posterior most parts of body about 1 mm, about 3 mm in median region (chaetigers 45–199) ( Fig. 3C ). Three paratypes; one complete and two incomplete, with 154, 217 and 77 chaetigers, and 80, 124 and 48 mm long, respectively. Width at chaetiger 10 ranging from 3 to 6 mm (without parapodia); widest region (chaetigers 14–18) ranging from 4 to 8 mm (without parapodia).

DESCRIPTION. Species description based on holotype except for jaw apparatus and external head morphology. Description of jaw apparatus based on paratype NHMO C6964 and head morphology on paratype NHMO C6966.

Live specimens beige in color with numerous brown spots on dorsal side of body and golden spots in folds between segments; anterior region with darker pigmentation (brown) on dorsal side, becoming lighter with disappearance of brownish spots ventrally. Branchial filaments white. Prostomium darker in center and lighter toward distal end, with brown patches ( Fig. 2A ). Prostomial appendages brown at proximal ends gradually becoming lighter towarddistalends, withtipswhite. Reddish-brown dark line extending along ventral side. Color pattern fading in recently fixed specimens.

Body long with width nearly the same along body, with tapering anterior and posterior ends. Cross section rounded at anterior and middle regions, flattening posteriorly.

Chaetigers about seven times wider than long at widest body region. Prostomium equal in length, narrower than peristomium, rounded, retracting beneath nuchal collar as far as bases of antennae. Median sulcus conspicuously visible at anterior dorsal and ventral sides. One pair of eyes present lateral to lateral antennae.

Five prostomial appendages arranged in shallow arc appearing wrinkled under stereomicroscope. Two lateral antennae longest, folding back until chaetiger 4. Median antenna posterior to lateral antennae, folding back until chaetiger 3, reaching beyond prostomium by about half of their length. Palps short, folding back reaching anterior margin of first peristomial ring. Ceratostyles and palpostyles digitiform, with peduncle. Ceratophores and palpophores consisting of single ring ( Fig. 2A, B, C ).

Separation between peristomial rings distinct on all sides. Second peristomial ring about one third of total length of peristomium. Peristomial ventrolateral lips distinct laterally as elevated surface. Ventral lips of peristomium swollen, having six longitudinal ridges with ventroanterior margin forming shallow arc ( Fig. 2A, D ).

Posterior end of muscularized pharynx reaching chaetiger 4. Calcareous cutting plates of mandibles longer than sclerotized matrix, with central margin being thinner than remaining part of plate ( Fig. 2E, I, J ). MxI more than twice as long as carrier, with white tips; MxII with lateral tapering prominence and white tips on first two teeth; MxIII arched and partly locating ventrally to MxII. Left MxIV wider than long. Attachment lamella of left MxIV following two plates with semicircle shape ( Fig. 2H ). Maxillary formula: I=1+1, II=4+4, III=5+0, IV=4+6, V=2+1, VI absent ( Fig. 2C, F, G ).

Postchaetal lobes wide round and longer than prechaetal lobes along whole body ( Fig. 3A ). Notopodial cirri digitiform and longer than chaetal lobes along whole body. Ventral cirri with rounded tip and inflated base along whole body, shorter than chaetal lobes and notopodial cirri ( Fig. 3C ). Branchiae start from chaetiger 29, palmate with two filaments from chaetigers 29–34 and three filaments from chaetigers 35– 47; short at first, gradually increasing in length posteriorly. Pectinate branchiae with four filaments from chaetigers 48–58, with five filaments from chaetigers 59–87, longest with maximum of six filaments from chaetigers 88–105. After chaetiger 105, both number and length of filaments decrease. From chaetiger 143–149 branchiae becoming palmate again. In last 48 chaetigers, branchial filaments absent ( Fig. 3A, B ). In best-developed branchiae, branchial filaments about three times longer than notopodial cirri and at least two times longer than branchial stems.

Four neuropodial aciculae present in all parapodia ( Fig. 3C, D ); three aciculae black and one aciculum yellow in color, with pointed distal ends. Neurochaetal lobes round along whole body. Chaetae forming two distinct bundles in all segments: supraacicular with limbate and pectinate chaetae ( Fig. 3E, F ), subacicular with compound spinigers and limbate chaetae ( Fig. 3E, F, G ). Pectinate chaetae present in anterior and middle body regions isodont, narrow with about 19 short and fine teeth. Posterior chaetigers with three types of pectinate chaetae; isodont, narrow with about 15 short and fine teeth ( Fig. 3H , 1 ), isodont, wide with about nine long and fine teeth ( Fig. 3I , 2 ), and anodont, wide with about six long and thick teeth ( Fig. 3J, 3 ). Subacicular hooks absent. Pygidium longer on dorsal side with one pair of tapering pygidial cirri.

REMARKS. The presence of limbate chaetae and compound spinigers in the subacicular chaetal bundle along the whole body differentiates M. aegypti sp.n. from M. sanguinea and all other known species of the M. sanguinea group ( Glasby, Hutchings, 2010), which have only compound spinigers in the subacicular chaetal bundle. Marphysa sanguinea sensu Hutchings & Karageorgopolous (2003) has dorsal and ventral anal cirri, while in the new species only one pair of anal cirri is present.

The presence of both compound spinigers and limbate chaetae in the subacicular chaetal bundle along the whole body differentiates M. aegypti sp.n. from all previously described species of the M. teretiuscula group ( Glasby, Hutchings, 2010). Marphysa mossambica Peters, 1854 differs from M. aegypti sp.n. in lacking narrow pectinate chaetae in the anterior chaetigers, and true compound chaetae (either bidentate falcigers or spinigers) along the whole body ( Glasby, Hutchings, 2010). In addition, M. mossambica has bidentate sub-acicular hooks which are absent in M. aegypti sp.n. ( Fauchald, 1987; Glasby, Hutchings, 2010). Marphysa graveleyi Southern, 1921 has only a single type of pectinate chaetae with numerous teeth and lacks subacicular limbate capillaries in the anterior chaetigers ( Glasby, Hutchings, 2010).

In contrast to M. aegypti sp.n. M. fauchaldi Glasby et Hutchings, 2010 lacks compound spinigers in the subacicular bundle of the posterior chaetigers, and possesses single subacicular hook in posterior chaetigers. Additionally, M. fauchaldi has only one or two types of pectinate chaetae: one with many small teeth (always present) and the other with fewer larger teeth, which may be present or absent. Also, neuroaciculae are not identical in number throughout the body as they are reduced to one in posterior chaetigers. Moreover, the pygidium bears two pairs of pygidial cirri ( Fauchald, 1987; Glasby, Hutchings, 2010).

Marphysa belli Audouin et Milne Edwards, 1833 is another Marphysa species, which has been reported from the Northeastern Mediterranean coast of Egypt ( Abd-Elnaby, 2009b). M. belli specimens have compound spinigerous and falcigerous subacicular chaetae, and thus can be easily distinguished from M. aegypti sp.n.

Marphysa californica , which is the sister species to M. aegypti sp.n. in the molecular analyses ( Fig. 4 ), belongs to the M. sanguinea group. It differentiates from M. aegypti sp.n. in lacking anal cirri. In the anterior chaetigers of M. californica , the pectinate chaetae are few and difficult to see and bear numerous fine teeth similar to M. aegypti sp.n., but in the posterior segments only two forms of pectinate chaetae are present: one like those on anterior segments, and the other form with few coarse teeth. Marphysa californica lacks the third type of pectinate chaetae characteristic for M. aegypti sp.n ( Fig. 3J, 3 ). The maxilla IV of M. aegypti sp.n. bears six teeth on the right side, while in the M. californica it bears seven or eight blunt conical teeth.

Morphological and molecular data agreed in the recognition of a Marphysa species new to science with four individuals collected from the three Egyptian locations. The four specimens of M. aegypti sp.n. shared the same diagnostic features (see species description). All diagnostic characters lacked intraspecific variation but, admittedly, only a small number of specimens were investigated.

The COI dataset comprised the four specimens from Egypt plus 365 sequences of different eunicid species. The total number of positions before masking was 663 potentially homologous positions. After masking, 505 positions remained and, therefore, 23.8% of the positions were masked. This was mainly due to the relatively short COI sequences for some Lysidice Lamarck, 1818 species, so that these were positions that were trimmed from the ends of the alignment. The final dataset had only 5.6% of undetermined characters.

The intraspecific pairwise genetic distance of the four individuals of M. aegypti sp.n. was 0.001±0.001. The average pairwise genetic distance over all Marphysa species to each other is 0.1788±0.016. Specifically, comparing M. aegypti sp. n. with other Marphysa species, the average pairwise genetic distance was 0.1765± 0.016 and the minimum distance was to M. disjuncta Hartman, 1961 (0.1093±0.013).

Based on the MRE-based bootstopping criterion a proportion of 350 bootstrap replicates were sampled and the final ML optimized likelihood score of the best tree was -lnL 14893. 567380. The ML tree based on the COI dataset ( Fig. 4 ) revealed that the four individuals of M. aegypti sp. n. grouped together with bootstrap support of 100. Marphysa aegypti sp. n. clustered within Marphysa with a bootstrap support of 84 for the monophyly of the genus Marphysa . Within Marphysa , M. aegypti sp.n. was part of a clade also comprising M. californica , M. bifurcata Kott, 1951 , M. brevitentaculata Treadwell, 1921 , M. mullawa , M. viridis , M. sanguinea and M. coralline Kinberg, 1865 . Within this clade M. aegypti sp. n. is the sister group of M. californica with a bootstrap support of 73.

TYPE LOCALITY. Egypt; Suez Canal, Al ferdan (N 30°40 ”12.4"/ E 32°20 ”06.8).

HABITAT. Intertidal to 5 m depth, on mudflats.

BIOLOGY. Individuals are aggregated, and it is more difficult to obtain anterior ends than posterior ends.

ETYMOLOGY. Marphysa aegypti refers to Egypt (latin aegyptus) in the genetive (possisive) form meaning the “egyptian Marphysa ”.

Figures

Fig. 2. Marphysa aegypti sp.n. headappendages.A — anterior end of the holotype, dorsal view; B — anterior end of the paratype NHMO C6966, dorsal view; C — anterior end of the paratype NHMO C6965, everted jaws, dorsal view; D — anterior end of the holotype, ventral view; E — anterior end of the paratype NHMO C6964 (also shown in F–J), everted jaws, ventral view; F and G — maxillary apparatus, dorsal view; H — maxillary apparatus, ventral view; I — mandibles, dorsal view; J — mandibles, ventral view. Abbreviations: La — lateral antenna; Ma — median antenna; P — palp; E — eye; Cp — cutting plate; I–V — number of maxillary element; Al — attachment lamella. Рис. 2. Придатки головы у Marphysa aegypti sp.n. A — передний конец тела голотипа, вид с дорсальной стороны; B — передний конец тела паратипа NHMO C6966, вид с дорсальной стороны;

Fig. 3. Marphysa aegypti sp.n. body appendages and chaetae. A — right parapodium, anterior view, chaetigers 30 to 34; B — pectinate branchiae, chaetigers 139 to 142, posterior region of the holotype; C — right parapodium from chaetiger 12, posterior view; D — notopodial aciculae; E — chaetal bundles of a right parapodium, chaetiger 27; F — simple limbate chaetae, right parapodium, chaetiger 27; G — compound spinigers, right parapodium, chaetiger 27; H — isodont pectinate chaetae, narrow with short and fine teeth, chaetiger 18 (type 1); I — isodont pectinate chaetae, wide with long and fine teeth, and anodont pectinate chaetae, wide with long and thick teeth, chaetiger 165 (type 2 and 3 respectively); J — anodont pectinate chaetae, wide with long and thick teeth, chaetiger 170 (type 3). Abbreviations: PCL — postchaetal lobe; Brc — branchiae; Ntp — notopodial cirrus; Vc — ventral cirrus; Lp — length of postchaetal parapodia lobe; Ac — acicula; Sup a — supraacicular chaeta; Sub a — subacicular chaeta; 1 — isodont pectinate chaetae, narrow with short and fine teeth; 2 — isodont pectinate chaetae, wide with long and fine teeth; 3 — anodont pectinate chaetae, wide with long and thick teeth.

Fig. 1. Map of localities and distribution of Marphysa species. A — localities and distribution of Marphysa sanguinea species complex based on the records in WoRMS (World Register of Marine species; www.marinespecies.org) as well as literature. M. sanguinea — black; B — localities and distributions of other Marphysa species discussed in the paper. M. elityeni — brown; M. kristiani — pink; M. acicularum — red; M. nobilis — grey; M. viridis — black; M. bifurcata — purple; M. mossambica — green; M. californica — orange; M. brevitentaculata — yellow; M. belli — turquoise; C — sampling localities of the new species M. aegypti sp.n. (red). The maps were generated based on Google maps.

Fig. 4. ML tree based on cytochrome oxidase I (COI) sequences. Bootstrap support values above 50 are shown at the branches; terminals with more than three specimens from the same species are collapsed into a terminal triangle (except for Marphysa aegypti sp.n.). Height of the triangle corresponds to length of the longest path from the root of the species to a single specimen.Sequence accessionnumbers are provided after species names. Рис. 4. Филогенетическое дерево, построенное методом максимального правдоподобиЯ на основа- нии последовательностей цитохром оксидаЗы I (COI). Бутстреп-поддержки более 50 укаЗаны на ветвЯх; клады с тремЯ и более особЯми сколапсированы в терминальный треугольник (кроме Marphysa aegypti sp.n.). Высота треугольника соответствует длине наибольШей ветви от корнЯ вида. Регистрационные номера сиквенсовых последовательностей добавлены после видовых наЗваний.