Phylladiorhynchus iphiclus, 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 : 58-59

Phylladiorhynchus iphiclus n. sp.

( Figs. 20 , 21G )

Type material. Holotype. French Polynesia. BENTHAUS Stn DW 1894, 27.6688°S, 144.3585°W, 100 m, 8 November 2002: ov. F 2.3 mm (MNHN- IU-2019-2662).

Paratype. Vanuatu, SANTO, no station: 1 M broken (MNHN-IU-2019-2651) .

Etymology. From the name Iphiclus, an Argonaut, son of Phylacus and Clymene. The name is considered a substantive in apposition.

Description. Carapace: as long as broad; transverse ridges scattered and indistinct, without setae. Gastric region flattened and smooth, transverse ridges barely distinct: epigastric ridge indistinct, with 2 median spines; 2 lateral scales on anterior protogastric region. Mid-transverse ridge not interrupted, medially depressed, preceded by distinct cervical groove, followed by 1 not medially interrupted ridge and 1 short lateral ridge. Lateral margins slightly convex, with 4 spines: first anterolateral spine well-developed, reaching end of lateral orbital spine, hepatic margin unarmed; anterolateral spine followed by 3 branchial spines (2 anterior and 1 posterior spines). Rostrum triangular, horizontal, dorsally flattish or slightly concave, 1.2–[1.3] × as long as broad, length0.3 and breadth0.3 that of carapace; lateral margins smooth and straight, with well-developed supraocular spines, subapical spines absent. Pterygostomian flap ending in round, upper margin smooth.

Thoracic sternum: As wide as long. Sternite 3 moderately broad, [2.2]–2.5 × as wide as long, anterior margin with obtuse median projection, anterolaterally rounded. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width 2.1–[2.3] × that of sternite 3, 2.8–[3.2] × as wide as long.

Pleon: Transverse ridges with a few scattered short setae. Tergites 2–3 with anterior transverse ridge only; tergites 4–6 smooth.

Eye: Eyestalk as broad as long, peduncle not setose, cornea very expanded distally, maximum corneal diameter 1.3 × rostrum width, [1.2]–1.3 × maximum peduncle width.

Antennule: Article 1 1.3 × longer than wide, with 4 spines: distomesial spine small, distolateral spines with a blunt process or granule (no double or very small distolateral spine); proximal lateral spine small, always present.

Antenna: Article 1 with prominent mesial process distally clearly not reaching lateralmost antennular spine. Article 2 with distinct distal spines laterally and mesially. Article 3 with distomesial spine. Article 4 unarmed.

Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus [0.7] × length of ischium, extensor margin unarmed, flexor margin with 3 spines, decreasing in size distally.

P1: 2.8 male, [2.5] (female) × carapace length; subcylindrical, spiny and with scattered long stiff setae and some thick iridescent setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus as long as carapace, 1.5–[1.7] × as long as carpus. Carpus 1.8– [2.5] × as long as wide. Palm 0.8–[0.9] × carpus length, [1.5]–1.6 × as long as broad. Fingers as long as palm length, fixed finger with distal spine on lateral margin; movable finger with 2 basal spines.

P2–4: Slender, subcylindrical, moderately 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, [0.8] or as long as carapace length, [5.2]–5.4 × as long as broad, 1.3–[1.5] × as long as P2 propodus; P3 merus 5–[5.3] × as long as broad, 1.1–[1.6] × as long as P3 propodus; P4 merus 4–[4.8] × as long as broad, 1.1–[1.2] × 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 but unarmed other than small distal spine; flexor margins of all legs irregular, with distal spine; P4 lateral surface with median row of 2 small spines, absent in others. Carpi with 2 spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–3, smaller on P4; flexor margin unarmed. Propodi slender, [5.0–5.5]5.6–7.0 × as long as broad; extensor margin irregular, usually armed with a 1–2 proximal spines on P2–4; flexor margin with 3–4 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 4–6 movable spines.

Eggs: Ov. F (MNHN- IU-2019-2662) carried 10 eggs of 0.4 mm diameter

Live colour. Unknown.

Genetic data. No data.

Distribution. French Polynesia and Vanuatu, 100 m.

Remarks. Phylladiorhynchus iphiclus is easily distiguished from the other species by having the Mxp3 merus with 3 prominent spines along the flexor margin, the rostrum triangular and 2 spines on the epigastric ridge. Phylladiorhynchus iphiclus resembles to P. boucheti , from Chesterfield Islands, however, they can be distinguished by the following characters:

- The epigastric ridge has 2 spines in P. iphiclus , whereas there are 4 spines in P. boucheti .

- The gastric ridges are obsolescent or absent in P. iphiclus , whereas the protogastric and mesogastric ridges are distinct in P. boucheti .

- The carapace anterior margin has 2 spines in P. iphiclus , whereas there are 3 spines in P. boucheti .

- The flexor margin of Mxp3 merus is armed with 3 spines, whereas there are 2 spines in P. boucheti . Furthermore, the extensor margin is unarmed in P. iphiclus , having a distal spine in P. boucheti .

Figures

FIGURE 20. Phylladiorhynchus iphiclus n. sp., holotype ovigerous female 2.3 mm (MNHN-IU-2019-2662): A, carapace and pleon, dorsal view. B, thoracic sternites 3 and 4. C, right cephalic region, showing antennular and antennal peduncles, ventral view. D, left Mxp3, lateral view. E, left P1, dorsal view. F, right P2, lateral view. G, right P3, lateral view. H, right P4, lateral view. I, dactylus of right P2, lateral view. Scale bars: 1.0 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.