Mycale (Aegogropila) prognatha, Van & Aryasari & De, 2021

Van, Rob W. M., Aryasari, Ratih & De, Nicole J., 2021, Mycale species of the tropical Indo-West Pacific (Porifera, Demospongiae, Poecilosclerida), Zootaxa 4912 (1), pp. 1-212 : 20-23

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Mycale (Aegogropila) prognatha


Mycale (Aegogropila) prognatha sp.nov.

Figs 9 View FIGURE 9 a–d, 10a–g

Material examined. Holotype ZMA Por. 15822, Mauritius, Chenal du Trou d’Eau Douce , reef, 20.24°S 57.80°E, depth 8–10 m, coll. J.H. Stock, 7 February 1964 (color violet). GoogleMaps

Description. Lobate, massive ( Fig. 9a View FIGURE 9 ), consolidating algae and bryozoans, which provide much of the support. Size of the mass 10 x 5 x 2 cm. Live color cited as violet by its collector, orange beige in alcohol. Surface optically smooth, slightly bumpy, generally lipostomous, but with a few slightly raised oscules. Consistency firm, probably due to the enclosed algae and bryozoans.

Skeleton. The usual ectosomal aegogropila-skeleton ( Fig. 9b View FIGURE 9 ) of intercrossing spicule tracts is present. Tracts are 50–70 µm in diameter (8–10 spicules), forming meshes of 300–600 µm in size. Rosettes of anisochelae I are common in the ectosome and are 60–110 µm in diameter. Few subectosomal spicule tracts are present, only some bundles supporting the ectosomal skeleton. The choanosomal skeleton is largely replaced by algal thallus threads ( Fig. 9c View FIGURE 9 ), with many loose megascleres and microscleres strewn among them.

Spicules ( Figs 9d View FIGURE 9 , 10 View FIGURE 10 a–g). Mycalostyles, anisochelae in three categories, sigmas in two categories, toxas and toxodragmas.

Mycalostyles ( Figs 10a,a View FIGURE 10 1 View FIGURE 1 ), similar to those of M.(Ae.) orientalis : moderately robust, with faint constriction below an elongated, barely swollen head, 318– 342.9 –381 x 8– 10.3 – 11 µm.

Anisoschelae I ( Fig. 10b View FIGURE 10 ), rather robust, alae well-developed, and the shaft straight and free for about 45% of the spicule length, with outwardly curved upper median alae, 49– 52.3 – 57 µm.

Anisochelae II ( Figs 10c View FIGURE 10 ), differentiated in two overlapping types, one approximately similar to those of M. (Ae.) orientalis with narrow shape and broad median alae, the other more robust, with upper median ala rather narrow and the upper lateral alae broadly developed, with lower median ala broad and with slightly incurved rim, the two types in overlapping sizes, 23– 26.4 – 30 µm .

Anisochelae III ( Figs 10d,d View FIGURE 10 1 View FIGURE 1 ), characteristically with upper median ala overlapping the lower median ala, and tapering proximally towards a pointed ending, lower median ala with median protrusion; free shaft approximately 1/3 of the length of the spicule, size rather uniform, 9– 12.6 – 14 µm.

Sigmas I ( Fig.10e View FIGURE 10 ), robust, rather narrow, with strongly curved apices, 96– 107.1 – 111 µm, up to 10 µm in thickness.

Sigmas II ( Figs 10f View FIGURE 10 ), thin, rather evenly curved, in a large size range but not clearly divisible in size categories, 15– 24.3 – 36 µm.

Toxas ( Figs 10g,g View FIGURE 10 1 View FIGURE 1 ), shallow-curved, in a large size range but not clearly divisible in separate sizes, smaller toxas partially arranged in toxodragmas ( Figs 10g View FIGURE 10 1 View FIGURE 1 ), tending to be diamond-shaped (‘double’ toxodragmas), sizes 36– 64.9 – 132 µm, the larger sizes have a thickness up to 2 µm.

Etymology. The species name is an adjective derived from ‘prognath’, a medical term referring to a protruding jaw condition in humans. We consider this an apt description of the condition found in the anisochelae III.

Distribution and ecology. Mauritius, shallow reef locality.

Remarks. The specimen resembles specimens assigned here to M. (Ae) orientalis , but it differs substantially in (1) having two shapes of anisochelae II, (2) prognath anisochelae III, and (3) toxodragmas. The skeleton is also peculiar in being fortified by algal thallus. Live color is violet in stead of the orange color in M. (Ae.) orientalis . There is resemblance in anisochelae II between the two Oman specimens of M. (Ae.) orientalis , which are also relatively robust, perhaps evidence of the existence of a distinct Indian Ocean population which could include the present specimen. However, additional features such as the toxodragmas, and especially the peculiar shape of anisochelae III, are absent in these specimens.

Mycale aegagropila sensu Wilson 1925 , here considered to belong to M. (Ae.) orientalis , was mentioned to possess a few toxodragmas, a further indication that our new species is close to M. (Ae.) orientalis .

Prognath anisochelae III remind of the condition in the Caribbean species Mycale (M.) arndti Van Soest, 1984 as demonstrated in Hajdu & R̹tzler’s (1998) fig. 3g.


Universiteit van Amsterdam, Zoologisch Museum













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