Phylladiorhynchus spinosus 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 : 133-134

Phylladiorhynchus spinosus Schnabel & Ahyong, 2019

( Figs. 30D–F, O–P , 50I )

Phylladiorhynchus spinosus Schnabel & Ahyong, 2019: 338 , figs 13–14 (in part, excluding Western Australian material = P. asclepius n. sp.).

Phylladiorhynchus integrirostris . — Baba, 1991: 486 (in part), fig 4.

Material examined. New Caledonia CHALCAL 1 Stn DC 26, 19.1783°S, 158.5833°E, 48 m, 18 July 1984: 1 M 2.6 mm (MNHN-IU-2013-9439 (Ga-2055)).— Stn DC 55, 21.3983°S, 158.9933°E, 55 m, 25 July 1984: 1 M 2.9 mm (MNHN-IU-2016-473 (Ga-2056)).— Ouen Is. Prony Bay . Stn 121, 22.4666°S, 166.7183°E, 12 m, August 1984: 1 ov. F 3.7 mm (MNHN-IU-2019-2613).—Stn 242, 22.3666°S, 167.0366°E, 25 m, October 1984: 1 M 3.4 mm (MNHN-IU-2019-2619).—Lagon Est. Stn 713, 21.3766°S, 166.0116°E, 34–35 m, 11 August 1986: 1 M 3.3 mm (MNHN-IU-2016-492), 1 M 2.7 mm (MNHN-IU-2016-491).—Stn 782, 21.1016°S, 165.6116°E, 30 m January 1987: 1 M 2.7 mm (MNHN-IU-2019-2621) .

Chesterfield Islands . CORAIL 2 Stn DW 88, 19.1000°S, 158.9300°E, 32 m 26 July 1988: 1 F 2.9 mm (MNHN- IU-2016-469 (Ga-2052)).— Stn DW 160, 19.7666°S, 158.3833°E, 35–41 m, 1 September 1988: 1 M 2.5 mm (MNHN-IU-2016-470 (Ga-2054)) .

Diagnosis (modified from Schnabel & Ahyong 2019). Rostrum dagger-like, lateral margins nearly straight; subapical spines present. Carapace with 2 epigastric spines; metagastric ridge between third branchial marginal spines medially continuous; anterior branchial margin with 3 spines; hepatic spine present. Pleonal tergites 2–4 with anterior and posterior ridges. Thoracic sternite 3 anterior margin biconcave, with obtuse median projection. Antennular article 1 with 5 spines: distomesial spine large; second (proximal) lateral spine long, slender. Antennal article 1 mesial process distally falling well short of second lateral antennular spine; article 2 distolateral spine distinctly larger than distomesial spine; article 3 with small to minute distomesial spine, distolaterally unarmed. Flexor margin of Mxp3 merus with one prominent spine only. P1 very slender (P 1 male more than 3.5 × as long as carapace). P2–4 dactylus extensor margin with sharp upright spines at bases of movable spines.

Distribution. Eastern Australia from Queensland, the Norfolk Ridge and Norfolk Island, at 4–81 m (one record at 570–578 m). New Caledonia and Chesterfield Islands, from 12 to 55 m.

Remarks. Phylladiorhynchus spinosus belongs to the group of species characterized by the presence of 2 epigastric spines, 1 hepatic spine, 3 spines on the anterior branchial margin, the rostrum dagger-like (margin straights or nearly straight) and the presence of dactylar spines along the flexor margin of the P2–4 dactyli. There are 4 closely related species: P. asclepius from Western Australia, P. euryalus from Eastern Australia (Queensland), New Caledonia and Chesterfield Islands, P. lini from Taiwan and P. spinosus Schnabel & Ahyong, 2019 (also found in New Caledonia). The species from this complex are morphologically very similar, although genetically very distinct. However, they can be distinguished by the following subtle characters (sometimes overlapping):

- The dorsal carapace, pleonal ridges and ocular peduncles have many thick iridescent setae in P. asclepius , P. euryalus and P. spinosus , whereas these iridescent setae are absent in P. lini .

- The carapace is always wider than long in P. asclepius , whereas it is usually as long as or slightly longer than wide in the rest of the species.

- The rostrum is twice longer than wide in P. spinosus and P. asclepius , whereas it is less than twice longer than wide in P. euryalus and P. lini .

- The antennule proximal lateral spine is prominent in P. euryalus , reaching the mid-length of the lateral spine, whereas this spine is smaller in the other species.

- The anterior margin of thoracic sternite 3 is anterolaterally projected (biconcave with a median blunted triangular projection) in P. spinosus and P. euryalus , whereas this margin has a median projection and it is anterolaterally rounded in the remaining species.

- The spines of the antennal article 2 are subequal in P. asclepius , P. euryalus and P. lini , whereas the distomesial spine is minute in P. spinosus . Furthermore, the antennal article 3 is usually armed with a small to distinct distomesial spine in P. asclepius , whereas this spine is absent in the remaining species.

- The P1 is very slender in P. spinosus (P 1 male> 3.5 as long as carapace), moderately slender in and P. euryalus and P. lini (P 1 male about 3.0 as long as carapace), whereas it is moderately stout in P. asclepius (P 1 male <3.0 as long as carapace).

The genetic divergences between P. spinosus and other closely related species were around 8% (COI) and 6–7% (16S). The subtle morphological differences among specimens of P. spinosus from different localities were mentioned by Schnabel & Ahyong (2019). Unfortunately, we have not examined the type specimens of P. spinosus , but we suggest that this species is probably restricted to Queensland, Norfolk Ridge and Norfolk Islands area. Their material from Western Australia is probably referable to P. asclepius , although it should be confirmed in the future.

Figures

FIGURE 30. Variability in the armature of the antennal articles 2-4 (A-L) and in the shape of the thoracic sternite 3 (M-T). P. euryalus n. sp.: A, M, paratype male 1.8 mm (UF34732); B, paratype male 1.6 mm (UF25216); C, N, paratype female 3.5 mm (MNHN-IU-2016-489). P. spinosus Schnabel & Ahyong, 2019: D, O, male 2.7 mm (MNHN-IU-2016-491); E, male 2.6 mm (MNHN-IU-2013-9439); F, P, male 2.5 mm (MNHN-IU-2016-470). P. asclepius n. sp.: G, Q, holotype male 2.1 mm (UF22296); H, R, paratype ovigerous female 2.1 mm (UF27601); I, paratype male 2.4 mm (UF27886). P. lini n. sp.: J, S, paratype ovigerous female 2.6 mm (UF11812); K, T, paratype ovigerous female 2.5 mm (MNHN-IU-2016-490); L, paratype male 1.7 mm (MNHN- IU-2016-1490). Scale bar: 1 mm.

FIGURE 50. Rostrum, dorsal view. A, Phylladiorhynchus phlias n. sp., paratype male 1.4 mm (MNHN-IU-2014-13881). B, P. poeas n. sp., paratype male 3.3 mm (MNHN-IU-2014-13737). C, P. pollux n. sp., holotype ovigerous female 3.5 mm (MNHN-IU-2014-13797). D, P. porteri n. sp., paratype female 2.4 mm (MNHN-IU-2014-23831). E, P. priasus n. sp., paratype ovigerous female 2.1 mm (UF54422). F, P. pulchrus n. sp., paratype male 1.8 mm (MNHN-IU-2019-2675). G, P. punctatus n. sp., paratype male 1.7 mm (MNHN-IU-2019-20101). H, P. serrirostris (Melin, 1939), paralectotype male 2.3 mm (UPSTY2531). I, P. spinosus Schnabel & Ahyong, 2019, male 3.3 mm (MNHN-IU-2016-492). J, P. talaus n. sp., paratype ovigerous female 2.4 mm (WAM C43997). K, P. tiphys n. sp., holotype male 2.4 mm (MNHN-IU-2014-13794). L, P. zetes n. sp., holotype male 2.1 mm (UF30059). Scale bars: 1 mm.