Magelona montera, Mortimer, Kate, Cassà, Susanna, Martin, Daniel & Gil, João, 2012

Mortimer, Kate, Cassà, Susanna, Martin, Daniel & Gil, João, 2012, New records and new species of Magelonidae (Polychaeta) from the Arabian Peninsula, with a re-description of Magelona pacifica and a discussion on the magelonid buccal region, Zootaxa 3331, pp. 1-43 : 5-8

publication ID	https://doi.org/ 10.5281/zenodo.208658
DOI	https://doi.org/10.5281/zenodo.5658272
persistent identifier	https://treatment.plazi.org/id/EA76A055-FFA6-FF80-FF0A-D3560DE8FB07
treatment provided by	Plazi
scientific name	Magelona montera
status	sp. nov.

Treatment

Magelona montera View in CoL sp. nov.

Figures 1 View FIGURE 1 , 13 View FIGURE 13 E

Magelona cornuta View in CoL - Amoureux (1983: 737, Table 1); not Magelona cornuta Wesenberg-Lund, 1949 View in CoL

Material examined. Holotype: Northern Red Sea, ISRAEL, Eilat, Gulf of Aqaba, (approximately 29°33'N, 34°57'E), sand, intertidal ( MNHN A895; af), collected by D. Dexter, 5th July 1979.

Diagnosis. Prostomium longer than wide, with distinct prostomial horns, distal tips bulbous. Notopodia of chaetigers 1–8 with foliaceous postchaetal lamellae, with crenulated margins, expanded as cirriform dorsal superior processes. Neuropodia with triangular ventral lobes, chaetiger 8 with additional triangular postchaetal lamellae. Notopodia of chaetiger 9 with triangular postchaetal lamellae, ‘swollen’ distally, confluent with prechaetal ridges. Neuropodia of chaetiger 9 similar to preceding chaetiger, however, ventral processes prechaetal. All thoracic chaetae capillaries. Abdominal lateral lamellae subtriangular, basally constricted. Hooded hooks tridentate, in two groups, vis-à-vis.

Description. A moderately large species; thoracic-abdominal junction indistinct ( Figure 1 View FIGURE 1 A). Holotype, ovigerous, posteriorly incomplete, condition good. Prostomium 1.2 mm long, 0.95 mm wide; thorax 6.7 mm long (including prostomium), 0.6 mm wide; abdomen 0.55 mm wide; total length approximately 30 mm for 53 chaetigers, 53rd chaetiger now dissected and slide mounted.

Prostomium longer than wide (L:W ratio 1.26), rounded laterally; anterior margin smooth, triangular, with conspicuous prostomial horns ( Figures 1 View FIGURE 1 B, 13E); horn distal tips bulbous, distinctly separated from antero-lateral margins of prostomium. Two pairs of prominent longitudinal dorsal muscular(?) ridges, outer pair, abutting inners for entire length; inner pair diverging distally into horn corners. Outer pair, moderately thick, with distinct transverse ridges. Distinct quadrangular (muscular?) areas present either side of ridges. Proboscis partially everted, squashed and visible on left-hand side of body ( Figures 1 View FIGURE 1 A, 13E); spherical(?) (true shape difficult to discern due to condition); ridged, ridging much lighter superiorly. Both palps attached (right-hand palp slightly longer), highly coiled, long; arising ventrolaterally from base of prostomium, reaching approximately chaetiger 25; non-papillated region reaching chaetiger 4. Papillae: short proximally but long for majority of length; digitiform; proximally with two rows of papillae either side of inconspicuous groove, medially and distally with one row either side.

Achaetous region behind prostomium slightly longer than chaetiger 1. Chaetigers 1–8 similar; parapodia biramous; notopodia with low triangular prechaetal lamellae confluent with large foliaceous postchaetal lamellae of similar size throughout thorax (slightly larger on chaetigers 7 and 8), upper margins minutely crenulate (degree of crenulation, somewhat variable). Long slender, cirriform, prechaetal superior processes present (DML) ( Figures 1 View FIGURE 1 C–I). Neuropodial pre- and postchaetal lamellae as low ridges; ventral triangular lobes (VNL) with pointed distal tips, beneath chaetae, of similar size to the mid-thorax. Lobes decreasing in size on chaetiger 8 and occurring in a slightly prechaetal position, chaetiger 8 with additional postchaetal triangular lamellae.

Chaetiger 9: Notopodial prechaetal lamellae inferiorly encircling chaetae forming subtriangular postchaetal lamellae (smaller than those of chaetigers 2–8), with distinct ‘swollen’ tips; superior processes (DML) absent (Figure 1J). Neuropodia of chaetiger 9 similar to that of chaetiger 8; triangular postchaetal lamellae confluent with low prechaetal ridges and digitiform prechaetal lobes. Chaetae of all thoracic chaetigers simple winged capillaries.

Abdominal chaetigers with large subtriangular lateral lamellae with rounded tips, of about equal size in both rami ( Figures 1 View FIGURE 1 K–L); basally constricted, and overlapping in anterior abdomen. Postchaetal extension of the lateral lamellae behind chaetal rows well-developed in anterior abdomen; triangular. Triangular processes (DML and VML) present at inner margins of chaetal rows, long in anterior abdomen.

Abdominal chaetae tridentate hooded hooks ( Figures 1 View FIGURE 1 M–N) of similar size. Hooks in two groups, main fangs vis-à-vis ( Figures 1 View FIGURE 1 K–L). Around 8–12 hooks per rami, majority of hooks located in group at inner margins of chaetal rows. Single hook, smaller than ‘ordinary’ tridentate hook present at the bases of lateral lamellae.

Paired posteriorly open pouches present on consecutive segments from chaetiger 38. Pouches appear as simple folds, medially split with thicker cuticle surrounding edges. Eggs present in body cavity (visible on slide preparation of 53rd chaetiger), approximately 60 Μm in diameter. Eggs clearly separated from pouches by epidermis. Posterior unknown.

Colour. Colour of preserved specimen uniformly cream/white in alcohol. Methyl green stain dissipates quickly leaving a very diffuse, overall stain. However, dorsal transverse bands of light green persist between chaetigers 3–9, just posterior to parapodia. These correspond with white speckled transverse bands visible in the same area without staining (see Figure 1 View FIGURE 1 A). Similar light green bands are observed with methyl green in the abdomen, and additional dark green interparapodial patches. Ventrally, a diffuse dark stain of speckles between chaetigers 5– 7 (stronger between 5–6) and light green speckled patches either side of the mid-ventral line, just posterior to the level of the parapodia in the same region were observed.

Habitat. Type specimen found in intertidal sand, Eilat, Israel, Gulf of Aqaba.

Etymology. From the Spanish word, ‘montera’, for the hat typically worn by bullfighters/matadores, referring to the shape of the prostomial frontal horns.

Remarks. Sixteen species share morphological similarities with M. montera sp. nov., in the shape of the thoracic lamellae: Magelona berkeleyi Jones, 1971 , M. cornuta , M. crenulifrons , Magelona gemmata Mortimer & Mackie, 2003 , Magelona marianae Hernández-Alcántara & Solís-Weiss, 2000 , Magelona methae Nateewathana & Hylleberg, 1991 , Magelona nonatoi Bolívar & Lana, 1986 , M. pulchella , M. pacifica , Magelona tehuanensis Hernández-Alcántara & Solís-Weiss, 2000 , five undescribed species of Uebelacker & Jones (1984) (spp. D, G, J, K, L) and Magelona sinbadi sp. nov., described herein (see below).

The two species sharing the most morphological similarities with M. montera sp. nov., are M. marianae (from México) and M. pacifica (from Panamá, see below for re-description). Magelona marianae possesses thoracic notopodial lamellae with crenulate margins and distinct prostomial frontal horns, but differs from M. montera sp. nov., in the nature of chaetigers 8–9, and in possessing bidentate hooded hooks. The prostomium of M. pacifica shares many similarities with that of M. montera sp. nov., however differs in having a more triangular anterior margin; less bulbous distal tips of the frontal horns; and frontal horns which are not as wide (transversely). Both species share many similarities in terms of: lamellar shape; methyl green staining patterns and presence of paired posteriorly open pouches with a medial slit, on consecutive segments from approximately chaetiger 40. Magelona pacifica like M. montera sp. nov., possesses small abdominal triangular processes (DML and VML) at the inner margins of chaetal rows. However, M. pacifica differs in not possessing distinct crenulate upper margins of thoracic notopodial lamellae, and in possessing bidentate hooded hooks. The abdominal hooks of M. pacifica also appear to be in one unidirectional group (see below) differing from M. montera sp. nov., in which they are vis-àvis.

Magelona montera sp. nov., differs from M. pulchella , M. methae , Magelona spp. D and G and M. crenulifrons in possessing tridentate and not bidentate hooded hooks, and having crenulate thoracic notopodial lamellae. Magelona nonatoi , M. berkeleyi and Magelona sp. J, all differ from M. montera sp. nov., in possessing only rudimentary prostomial horns. Magelona cornuta , M. tehuanensis and Magelona sp. L possess well-developed frontal horns but differ from this new species in possessing crenulate anterior prostomial margins. Magelona gemmata , Magelona sp. K, and M. sinbadi sp. nov., have well-developed frontal horns but differ from the new species by not possessing crenulate thoracic notopodial lamellae. Magelona sp. K, and M. sinbadi sp. nov., further differ in the nature of their 9th chaetigers. The prostomial shape and nature of the frontal horns in M. montera sp. nov., is very distinct.

The presence of distinct ‘swollen’ tips on the postchaetal notopodial lamellae of chaetiger 9 as seen here in M. montera sp. nov., is a feature shared with M. gemmata from the Seychelles.