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In this study, some biological characteristics of the invasive moon crab, Matuta victor, which has recently entered the waters of the northeastern Mediterranean, Türkiye, were investigated for the first time. The study was carried out seasonally on sandy bottoms at 0.5-3 m depths along Karataş (Adana, Türkiye) coasts between 2020 -2021. A total of 364 crabs were obtained, 93 females (27 ovigerous), 270 males and one juvenile. The carapace width of female crabs ranged between 27.49-49.30 mm with a mean of 41.55±4.01 mm. The carapace width of male crabs ranged between 21.28-66.70 mm with a mean of 49.15±8.97 mm. Mean carapace length measurements in females and males were 26.83±2.52 mm and 32.71±5.85 mm, and the mean total weights were 8.18±1.99 g and 16.27±7.30 g, respectively. The male:female ratio was 2.16:1. Morphometric relationships indicated negative allometric growth for females, males, and both sexes. Ovigerous females were obtained in all seasons except the winter. The female crabs with carapace widths that ranged between 35.31-48.84 mm and a mean of 41.97±3.29 mm had a mean fecundity of 36822.04±29745.9 eggs.

Matuta species belong to the superfamily Calappoidea and are widely distributed in the Indo-Pacific region, including the New Hebrides, Fiji (from Southeast Asia) and the Red Sea. They live in sandy coastal areas and at depths between 0-20m. To date, the studies of Matuta victor have generally focused on the first record/occurrence. In addition, egg morphology and fecundity studies are limited due to the difficulty in encountering ovigerous female individuals. In this study, the number of eggs and egg morphology of an ovigerous female individual belonging to the M. victor species caught from Antalya Bay (in August 2022) were investigated. In the metric measurements, the length of the carapace was 2.53 cm, the width of the carapace was 2.62 cm, and the characteristic distance between the end points of the lateral spines on the carapace was 3.90 cm. The weight of the individual was measured as 7.380 g. The average diameter of 100 eggs was calculated as 331.75 ± 7.62 µm. The number of oil droplets observed in the eggs was 1 and the the oil drop diameter was measured as a minimum of 59.64 µm, a maximum of 73.12 µm and an average of 64.16±3.21 µm. The yolk diameter in eggs was measured as a minimum of 264.96 µm, a maximum of 299.56 µm and an average of 286.10±9.19 µm. The ratio of oil drop diameter to yolk diameter was calculated as 0.22±0.01 µm. Since there are very limited studies on M. victor in the Mediterranean, and there is no study on egg morphology and fecundity, especially in Antalya Bay, this study presents novel data that can be used for comparison in other egg morphology studies of M. victor or another species belonging to the same genus. [ABSTRACT FROM AUTHOR]

Two adult specimens of Matuta victor were recently collected in Haifa Bay, Israel. A single specimen of Ashtoret lunaris, collected in 1987 from Haifa Bay, was hitherto the only record of the Matutidae in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]