Nobiliella margaritata Galil & Innocenti 2019, n. sp.

Nobiliella margaritata n. sp.

(Figs 3A, B, 4D)

Material examined. Holotype, male (7.2 x 8.0), MZUF-4450, Eritrea, Massawa, Gurgussum, tidal zone, coll. L. Mares, Jan. 1975.

Description. Carapace (Fig. 3A) subrhomboidal, 1.1 times as wide as long, prominently ridged, margins and dorsal surface boldly granulate. Front produced, upturned, medially concave, finely granulate; margin tridentate. Upper orbital margin unifissured. Mesogastric region convex. Gastrocardiac region prominently raised; gastric region with granulate protuberances laterally; cardiac region with median prominent protuberance bearing large pearly granules. Intestinal region with median prominent protuberance bearing large pearly granules, raised higher than cardiac protuberance. Hepatic region weakly demarcated; margin concave, separated from rounded epibranchial margin by small V-shaped notch. Hepatic facet well developed, concave. Pterygostomial margin ventrally projecting. Epibranchial region sloping anteriorly from epibranchial ridge; margin boldly granulate, slightly upturned, convex. Epibranchial ridge conspicuous, granulate; extending obliquely from gastric protuberances to granulate protuberance on metabranchial margin. Metabranchial region concave; margin oblique, imperceptibly concave. Posterior margin obsoletely trilobate, forming obtuse angle with metabranchial margin. Ocular peduncle short. Antennule obliquely folded in fossa. Basal segment of antenna fused with infraorbital lobe. Lateral margin of buccal frame granulate, minutely notched anterolaterally. Third maxilliped flattened, densely granulate, mesial margins finely granulate; merus as long as ischium along mesial margin; exopod with longitudinal rows of pearly granules along medially, slightly arcuate. Surfaces of sub-orbital, pterygostomial, subhepatic and sub-branchial regions covered with pearly granules. Chelipeds and ambulatory legs missing. Thoracic sternites bearing large pearly granules anteriorly; first to fourth sternites fused; sutures between fourth and fifth sternites to seventh and eighth sternites interrupted medially; sternopleonal cavity reaching first segment, margin rimmed with pearly granules. Male pleon with first somite narrow, yoke-shaped; fused somites elongate, trapezoidal, medially convex proximally, large flattened granules on proximal margin, distal margin with triangular denticle at right angle to abdomen; telson elongate, tongue-shaped (Fig. 3B). G1 (Fig. 4D) slender, sinuous; proximal calcareous portion with long setae distally, corneous portion distally wider, lobular, mesially notched. G2 short, filiform, tip triangular.

Etymology. The specific epithet is from the Latin, margarita (pearl), for the pearl-like granules on its carapace. Used as an adjective.

Distribution. Known from a single male specimen from Massawa, Eritrea.

Remarks. Komatsu & Takeda (2003) transferred Nursia jousseaumei Nobili, 1905, and N. jousseaumei var. cornigera Nobili, 1905 (raising the latter to the specific rank), to a new genus, Nobiliella. Nobiliella margaritata n. sp. closely resembles its congeners in general body form, including granular dorsal ridges of the carapace and triangular tooth of the metabranchial margin, but it is easily distinguished from them by the extensive coverage of pearl-like granulation on both dorsal and ventral surfaces of the carapace. Additionally, N. margaritata n. sp. differs from N. cornigera in possessing tridentate rather than bilobate frontal margin (Komatsu & Takeda 2003: figs 3a,b, 4e), less prominent triangular tooth on metabranchial margin (Komatsu & Takeda 2003: figs 3a, 4e,f). Nobiliella margaritata n. sp. shares with N. jousseaumei the protruding triangular denticle distally on male abdomen (Komatsu & Takeda 2003: figs 1e, 4d), but differs in the shape of the G1 tip (Komatsu & Takeda 2003: fig 1g,h).