Phylladiorhynchus euryalus, Rodríguez-Flores & Macpherson & Machordom, 2021

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 : 38-41

Phylladiorhynchus euryalus n. sp.

( Figs. 13 , 21A , 30A–C, M–N )

Phylladiorhynchus integrirostris . — Baba 1991: 486 (in part, only specimens from CORAIL 2 Stn DW101 [MNHN Ga-2053], Stn CP23 [MNHN Ga-2048], Stn CP24 [MNHN Ga-2049]).

Type material. Holotype. Australia. Queensland, Heron Is. 23.4733°S, 151.9505°E, no depth, 17 November 2006: ov. F 2.8 mm ( UF25255 ).

Paratypes. Australia. Queensland, Heron Island . 23.4418°S, 151.9004°E, no depth, 16 November 2006: 1 M 1.8 mm ( UF34732 ) .— 23.5545°S, 152.0339°E, no depth, 16 November 2006: 1 F 1.1 mm ( UF26300 ) .— 23.4733°S, 151.9505°E, no depth, 17 November 2006: 1 F 1.8 mm ( UF25213 ) , 2 M 1.6–1.8 mm ( UF25216 ) , 1 ov. F 2.8 mm UF25255 ), 2 ov. F 2.1–2.3 mm ( UF25215 ) , 1 ov. F 2.7 mm ( UF25222 ) .

New Caledonia. Grand Recif Sud. Stn 296, 22.6833°S, 166.722°E, 26 m, November 1984: 2 F 2.3–3.5 mm (MNHN-IU-2016-489) .

Other material. New Caledonia. Ouen Is. Prony Bay . Stn 101, 22.5167°S, 166.5983°E, 18 m, August 1984: 1 ov. F 2.8 mm (MNHN-IU-2019-2618).—Grand Recif Sud. Stn 297, 22.6483°S, 116.7600°E, 30 m, November 1984: 2 M 3.2–3.3 mm (MNHN-IU-2019-2612).—Stn 304, 22.6633°S, 166.7983°E, 27 m, November 1984: 1 M 3.2 mm, 2 ov. F 3.5–3.6 mm (MNHN-IU-2019-2617).—Stn 338, 22.7450°S, 166.8183°E, 32 m, November 1984: 1 M 3.2 mm (MNHN-IU-2019-2611).—Stn 291, 22.6400°S, 166.7283°E, 31 m, November 1984: 1 M 2.7 mm (MNHN- IU-2019-2609).—Passe Sarcelle. 35–40 m, 1 ov. F 2.7 mm (MNHN-IU-2019-2610).—Lagon. Stn 336, 22.6917°S, 166.8567°E, 26 m, November 1984: 2 M 2.3–3.4 mm (MNHN-IU-2014-13911).—Recif Serrez. 7 m, 7 September 1992: 1 F 3.4 mm (MNHN-IU-2019-2615).—LIFOU Stn 1410, 20.9450°S, 167.0516°E, 2–4 m, 25 November 2000: 1 M 2.1 mm (MNHN-IU-2019-2604) .

Chesterfield Islands. CORAIL 2 Stn DW101, 19.1500°S, 158.4366°E, 37 m, 27 July 1988: 1 M 2.3 mm (MNHN-IU-2016-480 (Ga-2053)).—Stn CP23, 20.5100°S, 161.0600°E, 80–83 m, 22 July 1988: 2 ov. F 2.0– 2.1 mm (MNHN-IU-2016-479 (Ga-2048)).—Stn CP24, 20.4566°S, 161.0783°E, 74–75 m, 22 July 1988: 1 ov. F 1.9 mm (MNHN-IU-2016-471 (Ga-2049)).—Stn DW33,19.4166°S, 158.8683°E, 52 m, 23 July 1988: 1 ov. F 2.1 mm (MNHN-IU-2016-478).

Etymology. From the name Euryalus, an Argonaut, son of Mecisteus. The name is considered a substantive in apposition.

Description. Carapace: As long as or slightly longer than broad; transverse ridges with dense short setae and thick iridescent setae. Gastric region slightly convex with some transverse ridges: epigastric ridge distinct with 2 median spines and some lateral short scales, followed by small short scales on posterior epigastric region; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin, often followed by uninterrupted posterior protogastric ridge or short scales; anterior mesogastric ridge not medially interrupted, laterally interrupted by anterior branch of cervical groove, and continuing uninterrupted to first branchial spine, often followed by small scales; anterior metagastric ridge not medially interrupted, followed by posterior scalelike metagastric ridge. Mid-transverse ridge not interrupted, medially depressed, followed by shallow or indistinct cervical groove, followed by 2–3 not interrupted or minutely interrupted ridges, interspersed with 2 interrupted ridges and few short scales. Lateral margins convex, with 6 distinct spines: first anterolateral spine well-developed, reaching anteriorly to level of lateral orbital spine, second spine (hepatic) well-developed, slightly dorsomesially from lateral margin, and followed by 4 branchial spines (3 anterior and 1 posterior). Rostrum dagger-like, horizontal dorsally flattish or slighly concave [1.5]–1.9 × as long as broad, length [0.4]–0.5 and breadth [0.3]0.3 that of carapace; lateral margins serrated and straight or nearly straight, with well-developed supraocular basal spines and subapical spines. Pterygostomian flap with anterior spine, upper margin smooth.

Thoracic sternum: As wide as long. Sternite 3 moderately broad, 2.2–[2.3] × as wide as long, anterior margin convex, with blunted median projection, anterolaterally rounded to produced. Sternite 4 widely contiguous to sternite 3; anterolaterally smooth, surface depressed in midline, smooth; greatest width [2.7]–3.2 × that of sternite 3, [2.5]–4.0 × as wide as long.

Pleon: Elevated ridges with short setae and a few scattered long setae. Tergite 2–4 with anterior and posterior transverse elevated ridges; tergites 5–6 smooth.

Eye: Eyestalk length about 0.9–[1.1] × broader than long, peduncle distally setose, not distinctly expanded proximally, with few short transverse striae on lateral surfaces; cornea expanded distally, maximum corneal diameter 0.8–[0.9] × rostrum width, [0.8] as long as eyestalk.

Antennule: Article 1 longer than wide, with 5 distal spines: distomesial spine well-developed; proximal lateral spine prominent, reaching half-length of first lateral spine and overreaching distomesial spine, always present.

Antenna: Article 1 with prominent mesial process, distally falling well short of lateralmost antennular spine. Article 2 with well-developed distomesial and distolateral spines. Article 3 and 4 unarmed.

Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus [1.1] × length of ischium, with well-developed distal spine on extensor and flexor margins.

P1: Moderately slender, 2.6–3.1 (males), 2.0–[2.2] (females) × carapace length; subcylindrical, spiny and with long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus [0.7]–1.3 length of carapace, [1.4]–1.6 × as long as carpus. Carpus 1.5–[2.2] × as long as wide. Palm [1.0]–1.1 × carpus length, [2.0]–2.1 × as long as broad. Fingers 0.9–[1.1.] × palm length; fixed finger with 0–1 basal spines; movable finger often with basal spines or granules

P2–4: Setose and spinose. Meri successively shorter posteriorly: P3 merus [0.8]–0.9 × length of P2 merus, P4 merus [0.8]–0.9 × length of P3 merus. P2 merus, 0.6–[0.7] × carapace length, 3.6–[4.3] × as long as broad, 1.1–[1.4] × as long as P2 propodus; P3 merus [3.6]–3.7 × as long as broad, 1.1–[1.4] × as long as P3 propodus; P4 merus 3.2– [3.6] × as long as broad, 1.1 × as long as P4 propodus; extensor margin of P2 and P3 with row of spines, proximally diminishing, with prominent distal spine; P4 extensor margin irregular, unarmed; flexor margin irregular, with distal spine on P2–3, absent or small on P4. Carpi with 2–4 small spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–3, absent on P4; row of granules below extensor margin on lateral surface of P2–4; flexor margin unarmed. Propodi stout,3.0–4.0 × as long as broad; extensor margin irregular; flexor margin with 3–6 slender movable spines in addition to distal pair. Dactyli 0.6–[0.7] × length of propodi, ending in incurved, strong, sharp spine; flexor margin with dactylar spines at basis of 4–6 movable spines.

Eggs: Ov. F carried approximately 9– 20 eggs of 0.5–0.6 mm diameter.

Live colour. Unknown.

Genetic data. COI and 16S, Table 1.

Distribution. Australia, Queensland (Heron Islands), New Caledonia and Chesterfield Islands, from 2 to 83 m.

Remarks. Phylladiorhynchus euryalus belongs to the species-group having 2 epigastric spines, 1 hepatic spine, 3 spines on anterior branchial margin, rostrum dagger-like (margin straight or nearly straight) and dactylar spines along the flexor margin of the P2–4 dactyli. This species complex includes the following species: P. asclepius , from Western Australia, P. euryalus , from Queensland, New Caledonia and Chesterfield Islands, P. lini , from Taiwan, and P. spinosus Schnabel & Ahyong, 2019 , from New Zealand and New Caledonia. These species are morphologically very similar although genetically very distinct (see the differences under the Remarks of P. spinosus ).

The specimens of P. euryalus range from 1.6 to 3.6 mm postorbital carapace length. The six sequences of P. euryalus from Australia (Queensland) and New Caledonia diverged 1.3% for COI, four sequences diverged 0.7% for 16S.

Figures

FIGURE 13. Phylladiorhynchus euryalus n. sp., holotype ovigerous female 2.8 mm (UF25255): A, carapace and pleon, dorsal view. B, thoracic sternites 3 and 4. C, left cephalic region, showing antennular and antennal peduncles, ventral view. D, left Mxp3, lateral view. E, right P1, dorsal view. F, right P2, lateral view. G, left P3, lateral view. H, right P4, lateral view. I, dactylus of right P2, lateral view. Scale bar: A, E–H = 1.0 mm; B–D, I = 0.6 mm.

FIGURE 21. Rostrum, dorsal view. A, Phylladiorhynchus euryalus n. sp., paratype male 1.8 mm (UF34732). B, P. gustavi n. sp., paratype male 1.7 mm (UF9756). C, P. heptacanthus n. sp., holotype female 2.1 mm (MNHN-IU-2017-2534). D, P. hylas n. sp., paratype female 1.6 mm (MNHN-IU-2016-495). E, P. integrirostris (Dana, 1852), male 1.6 mm (UF15285). F, P. integrus (Benedict, 1902), ovigerous female 3.2 mm (MNHN-IU-2014-13853). G, P. iphiclus n. sp., holotype ovigerous female 2.3 mm (MNHN-IU-2019-2662). H, P. janiqueae n. sp., paratype male 1.8 mm (MNHN-IU-2016-482). I, P. jeffkinchi n. sp., paratype male 2.7 mm (MNHN-IU-2014-13565). J, P. joannotae n. sp., paratype male 2.1 mm (MNHN-IU-2014-20055). K, P. joannotae n. sp., holotype ovigerous female 2.1 mm (MNHN-IU-2014-13805). L, P. koumac n. sp., paratype male 1.5 mm (MNHN-IU- 2014-20121). Scale bars: 1 mm.

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.