Marphysa adenensis Gravier, 1900

Katsiaras, Nikolaos, Simboura, Nomiki & Koutsoubas, Drosos, 2014, The rare subgroup C 1 of Marphysa (Polychaeta, Eunicidae): re-description of species and first records in the Mediterranean Sea, Zootaxa 3873 (3), pp. 201-217 : 203-206

publication ID	https://doi.org/ 10.11646/zootaxa.3873.3.1
publication LSID	lsid:zoobank.org:pub:022136BF-394F-4959-8CE7-1F4971923223
DOI	https://doi.org/10.5281/zenodo.5613403
persistent identifier	https://treatment.plazi.org/id/03A75B37-9108-FFF0-07DB-FDEDFA7F7D01
treatment provided by	Plazi
scientific name	Marphysa adenensis Gravier, 1900
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Marphysa adenensis Gravier, 1900 View in CoL

Fig. 1 View FIGURE 1 a–h, 2a–d, 3, 4a–d, 5a–d, Table 2 View TABLE 2

Marphysa adenensis Gravier 1900: 270 View in CoL , Plate 14 Figures 91–92; Text-figures 140–143; Day 1962: 644; Day 1967: 399, Figures 17.6p–s

Type material. Holotype ( MNHN POLY TYPE 0531) from Aden Sea, 1900, 1 specimen, 45mm long and 0.75 width, 200 segments, posterior end missing, jaws removed.

Non-type material. Lesvos Island, Gera Gulf 15/9/2009: 3 specimens (GP-4B): 76 segments 30 mm long and 2.5 mm wide, 62 segments 24 mm long and 2.5 mm wide, 74 segments 25 mm long and 1mm wide; 1 specimen (GP-2B): in the 25 segments 30 mm long and 4 mm wide; Methoni 24/4/2012: 3 specimens (1/WFD 3R1): 54 segments 10.3 mm long and 1 mm wide, 43 segments 5 mm long and 1 mm wide, 35 segments 9 mm long and 1.5 mm wide; Lesvos Strait 29/3/2013: 1 specimens (3/WFD 70R1): 42 segments 20 mm long and 1.7mm wide.

Description. Holotype an anterior fragment of about 200 segments ( Fig. 5 View FIGURE 5 a). All 8 Mediterranean specimens anterior fragments; longest 30 mm long and 2.5 wide with 76 segments; shortest 5 mm long and 0.9 mm wide with 43 segments. Prostomium rounded anteriorly, as long as first peristomial ring, which is longer than second peristomial ring. Three antennae present and a pair of dorso-lateral palps. Antennae slightly longer than prostomium; median longer. Antennae arranged in slightly curved line and slightly articulated. Eyes present, positioned behind the lateral antennae. Jaws removed from holotype. Maxillary formula of Mediterranean material: I(1+1), II(5-7+7-8), III(6-7+0), IV (4+8) ( Fig. 3 View FIGURE 3 ).

Dorsal cirri cirriform in anterior body, more thin and slender after mid-body; slightly longer than the parapodium in anterior region, increasing in size up to twice as long after the first branchiae. Ventral cirri tongueshaped with rounded tips in anterior body, tips with a distal papilla in branchial segments, which gradually becomes less distinct after mid-body. Ventral cirri slightly shorter than the parapodium lobe. Post-chaetal lobes elongated and tongue-shaped, much longer than acicular lobe, gradually decreasing down to a similar length in posterior body. Pre-chaetal lobes always truncated and straight, shorter than acicular lobes. Branchiae present from chaetiger 10–17 until 16–32, depending on specimen size; all pectinate and have up to 10 filaments.

Holotype: Superior setae in each fascicle consist of: (1) 3–5 long capillaries, (2) 4–9 relatively shorter capillaries, (3) 1–2 heterodont pectinate setae, marginal teeth longer and unequal to each other (twice as long) throughout the body, with 4–5 teeth in anterior region ( Fig. 4 View FIGURE 4 c, 5c), increasing up to 7–8 towards the posterior end ( Fig. 4 View FIGURE 4 d). Inferior setae consist only of composite falcigers, bidentate and hooded ( Fig. 4 View FIGURE 4 b, 5b). There are up to 20 in anterior body, but only up to 10 at the posterior part. No composite spinigers present. Towards the posterior body, the number and length of all setae is decreasing, except of pectinate which remains the same. The length of the falciger blades is relatively short (32–40 µm in anterior chaetigers; decreasing down to 12–20 µm in posterior) and about equal between falcigers of the same fascicle, but with a slight length gradation (from 90µm up to 140µm) in the branchial region (one and half times longer). Aciculae blunt and pale. Acicular setae, beginning from chaetiger 35; pale yellow, hooded and bidentate; teeth have almost 90° angle between them; subdistal almost twice as wide ( Fig. 4 View FIGURE 4 a, 5d).

Mediterranean material: Superior setae in each fascicle consist of: (1) 3–5 long serrated capillaries ( Fig. 1 View FIGURE 1 a), (2) 4–9 short serrated capillaries, (3) 1–2 heterodont pectinate setae, marginal teeth longer and unequal to each other (twice as long) throughout the body, with 4–8 teeth in total ( Fig. 1 View FIGURE 1 f–h, 2c), regardless of specimen dimensions. Inferior setae consist only of serrated, bidentated and hooded composite falcigers. No composite spiniger present. In each fascicle of anterior body ( Fig. 1 View FIGURE 1 b, 2b), or until the mid-body in older individuals ( Fig. 1 View FIGURE 1 c), there are 3–4 falcigers with notably longer and thinner blades (up to 160 µm; 115.3 µm average in older, 68 µm average in younger specimens), more than twice as long as the other (up to 76 µm; 55.3 µm average in older, 34.6 µm average in younger specimens). The length and the number of all setae decrease close to the posterior end ( Fig. 1 View FIGURE 1 d), except the pectinate which remains the same. Aciculae blunt, pale yellow at the edge and dark brown at base; 2–3 per parapodium in anterior body, only 1 after the first branchiae. Acicular setae, beginning from chaetiger 22–35 (depending on specimen dimensions) are pale yellow, hooded and bidentate; teeth have almost 90° angle between them; subdistal almost twice as wide ( Fig. 1 View FIGURE 1 e, 2d).

Distribution. Red Sea: Aden ( Gravier 1900), Indian Ocean: Madagascar ( Day 1962), Reunion Island ( Bigot et al. 2008), Pacific Ocean: Hong Kong ( Mak 1980), Andaman Sea ( Aungtonya et al. 2002). Mediterranean Sea: Gera Gulf, Lesvos Island; Mytilene Strait (East Aegean Sea), Methoni (South Ionian Sea).

Ecology. Soft mud ( Madagascar), Muddy sand with sea-shells (Andaman Sea), coral communities ( Hong Kong). P. oceanica beds and two individuals have been found especially in shoot sheaths micro-habitat ( Greece).

Remarks. Marphysa adenensis is the first species of the genus described as having present only composite falcigers in inferior setae and branchiae limited to the anterior body. Although the blades of the falcigers are referred as “long and narrow” both in the original description and the subsequent description by Day (1963), no remarks are made for the presence of length gradation among the blades. The re-examination of the holotype in the present study showed that there is a length gradation in the branchial region. The Mediterranean specimens differ from the holotype by having a stronger gradation of falciger blades-length (more than twice as long, rather than one and half). However, there are a lot of falcigers missing blades in the holotype, after a century of preservation, especially in the first segments. Maxillary apparatus has been dissected out from the holotype, but the maxillary formula of the Mediterranean specimens differ from the published formula by Day (1967). In particular, the latter have more teeth in maxillary IV (4+ 8 in the Mediterranean specimens, than 7+ 11 in the holotype), as well as a slight variation in MxII (5-7+ 7-8 in the Mediterranean specimens, than 7+ 8 in the holotype) and in MxIII (6-7+0 in the Mediterranean specimens, than 7+0 in the holotype), varying according to body size. However, the published formula could be considered inadequate, since it seems to be based only on 3 individuals in total (the holotype from Aden; Gravier 1900 and two individual collected from Madagascar; Day 1962) and this number should not be enough to cover the interspecies variation. Besides the above differences, the Mediterranean specimens show important similarities with the holotype, namely in having: a) 1–2 pectinate setae all along the body, up to eight teeth, b) pale yellow acicular setae, hooded and bidentate with teeth that have almost 90° angle between them and the subdistal only slightly longer than the distal, but twice as wide. Marphysa adenensis is very similar to M. sp. A from the Gulf of Mexico. Although the personal examination of this species’ type materials was not possible, according to the published description ( Gathof 1984) the two species are very similar in terms of strong falciger blades-length gradation (twice as long in figure 40-14e–f), acicular shape (bidentate, hooded, 90° angle between the teeth and subdistal is wider than distal in figure 40-14h) and maxillary formula close to the interspecies variation (I:1+1, II:5-6+7, III:5-7+0, IV:2-4+5-12). The relation of Μ. sp. A to M. adenensis has to be defined in a future study, since there is a possibility to be a synonym species. Finally, it differs from the other species of Group C1 from America, M. conferta , mainly in having pectinate setae of fewer teeth (based on published description).