Palaemonella aliska Marin, 2008

(Fig. 5)

Palaemonella aliska Marin 2008: 376, figs. 1–5, 8a: Anker & De Grave 2019: 146, figs. 3, 4.

For additional synonymy of P. aliska referring to P. shirakawai see Okuno (2017).

Material examined. 1 female, pocl 3.4 mm, cl 5.5 mm, FLMNH UF 36078, Saudi Arabia, Makkah Province, Thuwal, southern end of Al Fahal reef, 22°13’21.7”N 38°58’03.7”E, exposed side of offshore reef, sand flat with abundant rubble, in burrow under large coral rock, depth: 1–3 m, leg. A. Anker et al., 19.03.2013 [fcn BDJRS-2974] .

Distribution. Widely distributed in the Indo-West Pacific ranging from the Red Sea (present study) to Vietnam (Marin 2008), Solomon Islands and Great Barrier Reef, Australia (Anker & De Grave 2019).

Ecology. The Saudi Arabian specimen was collected on a shallow reef flat (depth: 1–3 m) with abundance of coral rubble by flipping a large coral rock partly embedded in coarse sand; it was most likely dwelling inside a partly exposed burrow of a pair of goby-associated snapping shrimps ( Alpheus sp.). In Vietnam, Australia and the Solomon Islands, P. aliska inhabits burrows of Alpheus sciolii Anker, 2022 (Anker & De Grave 2019; Anker 2022c).

Remarks. The single specimen (non-ovigerous female) of P. aliska from Al Fahal reef off KAUST / Thuwal agrees very well with the detailed description of the species provided by Marin (2008), except for the presence of a distinct postorbital ridge, as mentioned above. The rostral formula of the Red Sea specimen is 6 / 2, with three teeth of the mid-dorsal carina situated posterior to the orbital margin (= postrostral teeth in Komai & Yamada 2015), thus falling within the range of variation reported by Marin (2008) and Anker & De Grave (2019). The colour pattern of P. aliska (Fig. 5; see also Marin 2008: fig. 9a; Anker & De Grave 2019: fig. 5A, B) is unique and therefore diagnostic, greatly facilitating identification of the species in the field. Noteworthy is that the Thuwal region of Saudi Arabia is currently the only locality in the world where three species of Palaemonella, viz. P. jamila sp. nov., P. aliska and another undescribed species of Palaemonella (Anker, in study) are found in association with burrowing snapping shrimps ( Alpheus spp.).