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| Parasesarma otiense Shahdadi, Hosie, Hara & Chan, 2025 |
Abstract
Nine species of Parasesarma are currently recorded from continental Australian mangroves. The present study describes a new species, P. otiense sp. nov., from Western Australia. Parasesarma otiense sp. nov. occurs sympatrically with P. hartogi and P. holthuisi in the mangroves of Exmouth Gulf. In both COX1 and 16S BI trees, the new species is well nested within Parasesarma, but divergent from other species. Morphologically, the new species is distinct from other Parasesarma in having eight asymmetric tubercles with the distal slope longer than the proximal slope on the upper surface of the cheliped dactylus. Parasesarma otiense is the tenth species of Parasesarma recorded from continental Australia, taking the number of species assigned to the genus Parasesarma to 59. A key to the species of Parasesarma known from Australian waters is provided to aid in their identification.
Key words: Crustacea, COX1, mangrove crab, molecular taxonomy, morphology, Parasesarma otiense
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| Parasesarma otiense sp. nov., holotype, WAM C74523, male (14.0 × 11.0), Western Australia, Exmouth Gulf, Bay of Rest mangrove. A. Dorsal habitus; B. Frontal view; C. Carapace, dorsal view; D. Pleon and mouth; E. Right chela, outer view; F. Left chela, dorsal view; G. Dactylus of right chela, dorsal view. |
Parasesarma otiense sp. nov.
Diagnosis. Ambulatory legs relatively long, P4 longest, ~1.7 × cw. Carapace rectangular, broader than long, dorsal surface smooth, front moderately deflexed, shallowly sinuous in dorsal view, median postfrontal lobes as wide as lateral ones. Eyestalk longer than wide, cornea wider than eyestalk. Chelipeds without subdistal spine on dorsal border of merus; male chela with 2 transverse pectinated crests on the upper surface of palm, dactylus with 8 asymmetric tubercles with proximal slope shorter than distal slope, tubercles with transverse keel and wrinkles. Male pleon triangular, somite 2 medially longer than lateral edges. G1 stout, straight, apical corneous process relatively long, bent at an angle of ~45° to vertical axis, aperture subterminal.
Etymology. The species name is derived from the Latin noun otium, meaning rest, and the gender-neutral suffix, -ense, in reference to the type locality, the Bay of Rest in Exmouth Gulf, Western Australia.
Adnan Shahdadi, Andrew M. Hosie, Ana Hara and Benny K. K. Chan. 2025. A New Species of Parasesarma (Brachyura, Sesarmidae) from Western Australia, with A Key to the Species from Australia. ZooKeys. 1255: 275-290. DOI: doi.org/10.3897/zookeys.1255.162897
