Phylladiorhynchus triginta Schnabel & Ahyong, 2019

Rodríguez-Flores, Paula C., Macpherson, Enrique & Machordom, Annie, 2021, Revision of the squat lobsters of the genus Phylladiorhynchus Baba, 1969 (Crustacea, Decapoda, Galatheidae) with the description of 41 new species, Zootaxa 5008 (1), pp. 1-159 : 138-139

Phylladiorhynchus triginta Schnabel & Ahyong, 2019

Phylladiorhynchus triginta Schnabel & Ahyong, 2019: 339 , figs. 12, 14.

Phylladiorhynchus integrirostris .— Ahyong, 2007: 42 , fig. 21.

Diagnosis (modified from Schnabel & Ahyong 2019). Rostrum lateral margins distinctly convex; subapical spines minute. Carapace with 2 epigastric spines; anterior branchial margin with 3 spines; metagastric ridge between third branchial marginal spines interrupted medially; anterior branchial margin with 3 spines; hepatic spine present. Anterior upper margin of pterygostomian flap usually smooth. Pleonal tergite 3 without posterior transverse ridge. Thoracic sternite 3 moderately broad, anterior margin biconcave, with obtuse median projection. Antennular article 1 with 5 spines: distomesial spine large; second lateral spine long, slender. Antennal article 1 mesial process falling well short of second lateral antennular spine; article 2 distolateral and distomesial spines well developed, subequal in length; article 3 with small to minute distomesial spine, distolaterally unarmed. Maxilliped 3 merus with 1 prominent spine on flexor margin. P2–4 dactylus extensor margin without upright spines at bases of movable spines.

Genetic data. COI, Table 1.

Distribution. Tasman Sea, Lord Howe Island, Middleton Reef and Norfolk Island at 10–84 m ( Schnabel & Ahyong 2019).

Remarks. The species belongs to the group of species with 2 epigastric spines, hepatic margin armed with 1 small spine and 3 spines along the anterior branchial margin. The closest relative is P. talaus , from Indonesia, Papua New Guinea, and Western Australia. The two species can be differentiated by the following characters:

- The rostrum has well-developed subapical spines in P. talaus , whereas these spines are minute in P. triginta .

- Thoracic sternite 3 is quadrangular (less than twice wider than long) in P. talaus , compared to moderately broad (twice as wide as long) in P. triginta .

The genetic divergence between P. triginta and P. talaus is very high, 27% (COI).