Phylladiorhynchus phanus, 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 : 107-110

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Phylladiorhynchus phanus

n. sp.

Phylladiorhynchus phanus n. sp.

( Figs. 33L View FIGURE 33 , 41 View FIGURE 41 , 55H View FIGURE 55 )

Type material. Holotype. Papua New Guinea. PAPUA NIUGINI Stn PB 12, 05.1966°S, 145.8133°E, 7–15 m, 30 December 2012: M 1.6 mm (MNHN-IU-2014-13812). GoogleMaps

Paratypes. Papua New Guinea. PAPUA NIUGINI Stn PS 02, 05.2016°S, 145.8216°E, 15–17 m, 6 November 2012: 2 F 1.1–1.4 mm (MNHN-IU-2019-2669).— Stn PD 19, 05.0900°S, 145.8083°E, 3–10 m, 13 November 2012: 2 M 1.3–1.7 mm, 1 ov. F 1.8 mm (MNHN-IU-2019-2665).— Stn PD 23, 05.1000°S, 145.8200°E, 3–7 m, 14 November 2012: 1 M 2.0 mm, 2 ov. F 1.8–2.2 mm (MNHN-IU-2014-13900).— Stn PD 24, 05.0883°S, 145.8100°E, 3–6 m, 14 November 2012: 2 ov. F 2.0– 2.2 mm, 2 F 1.4–2.0 mm (MNHN-IU-2016-450), 1 M 1.6 mm (MNHN- IU-2016-451).— Stn PB 08, 05.1833°S, 145.8066°E, 4–5 m, 30 December 2012: M 2.1 mm, 3 ov. F 1.8–2.2 mm (MNHN-IU-2019-2687) GoogleMaps .

Other material. Papua New Guinea. PAPUA NIUGINI Stn PD 25, 05.0833°S, 145.8183°E, 3–5 m, 14 November 2012: 1 M postlarva 0.9 mm, 1 F 1.5 mm (MNHN-IU-2019-2654).— Stn PB 19, 05.0850°S, 145.8100°E, 10 m, 16 November 2012: 3 M 1.0– 1.5 mm (MNHN-IU-2019-2673).— Stn PR 69, 05.0266°S, 145.8016°E, 2–15 m, 20 November 2012: 1 M 1.8 mm (MNHN-IU-2014-13811).— Stn PD 56, 05.1616°S, 145.8050°E, 2–5 m, 29 November 2012: 1 ov. F 1.6 mm (MNHN-IU-2019-2658).— Stn PR 129, 05.1883°S, 145.8250°E, 1–24 m, 29 November 2012: 1 ov. F 1.7 mm (MNHN-IU-2014-13899).— Stn PR 142, 05.1966°S, 145.8200°E, 2–18 m, 30 November 2012: 1 M 1.2 mm, 1 F 1.3 mm (MNHN-IU-2013-7074).— Stn PD 62, 05.1633°S, 145.8066°E, 1–3 m, 1 December 2012: 1 M 1.8–2.0 mm, 1 ov. F 1.8 mm (MNHN-IU-2014-13879).— Stn PD 79, 05.1166°S, 145.8083°E, 20 m, 10 December 2012: 1 M 1.5 mm, 1 ov. F 1.8 mm (MNHN-IU-2019-2671).— Stn PD 31, 05.0883°S, 145.8016°E, 1–6 m, 12–13 December 2012: 1 M 1.8 mm (MNHN-IU-2014-13878).— Stn PD 19, 05.0900°S, 145.8083°E, 3–10 m, 30 December 2012: 1 M 1.5 mm (MNHN-IU-2017-1343).— Stn PB 15, 05.0783°S, 145.8150°E, 5 m, 30 December 2012: 2 ov. F 1.5–1.6 mm, 1 F 1.8 mm (MNHN-IU-2019-2659).— Stn PB 08, 05.1833°S, 145.8066°E, 4–5 m, 30 December 2012: 1 ov. F 1.6 mm (MNHN-IU-2013-355), 1 M 1.4 mm, 6 ov. F 1.8–2.2 mm, 1 F 1.7 mm (MNHN- IU-2016-454), 1 M 1.4 mm (MNHN-IU-2014-13898).— Stn PS 31, 05.1361°S, 145.8236°E, 10–37 m, 30 December GoogleMaps

2012: 1 M 1.3 mm (MNHN-IU-2013-861).—Stn PS15, 05.0965°S, 145.8032°E, 12 m, 30 December 2012: 1 M 1.7 mm, 1 ov. F 1.9 mm (MNHN-IU-2019-2672).—Stn PB37, 05.2650°S, 145.7850°E, 10 m, 30 December 2012: 1 ov. F 2.3 mm (MNHN-IU-2016-1483).—Stn PS08, 05.1839°S, 145.8071°E, 8 m, 30 December 2012: 1 M 1.4 mm, 1 ov. F 1.4 mm, 7 F 1.0– 1.4 mm (MNHN-IU-2014-13864).—Stn PB19, 05.0850°S, 145.8100°E, 10 m, 30 December 2012: 2 M, 1.4–1.8 mm (MNHN-IU-2014-13880).—Stn PS23, 05.0762°S, 145.8201°E, 21 m, 30 December 2012: 1 M 1.7 mm (MNHN-IU-2019-2657).—Stn PB24, 04.9850°S, 145.7933°E, 1 m, 30 December 2012: 1 M 1.3 mm (MNHN-IU-2019-2656).—Stn PB53, 05.1350°S, 145.8033°E, 3 m, 30 December 2012: 1 F 1.5 mm (MNHN-IU- 2019-2655).—KAVIENG Stn KB54, 02.5316°S, 150.4583°E, 11 m, 20 June 2014: 1 ov. F 2.5 mm (MNHN- IU- 2014-2893).

Etymology. From the name Phanus, an Argonaut, son of Dionysus and Ariadne. The name is considered a substantive in apposition.

Description. Carapace: Robust or massive, sexually dimorphic (wider on females) 0.9–[1.0] (males), 0.7– 0.9 (females) × as long as broad; transverse ridges elevated, upraised dorsally, with short setae and scattered thick setae. Gastric region convex (upraised) with some transverse ridges: epigastric ridge unarmed, scale-like, continuing laterally with few small scales, often indistinct; anterior protogastric ridge not medially interrupted, laterally interrupted with some scales, often followed by some short scales; anterior mesogastric ridge scale-like, laterally interrupted by anterior branch of cervical groove, continuing with few scales, often followed by some short scales; anterior metagastric ridge medially uninterrupted, laterally interrupted, followed by some scales on posterior metagastric region. Mid-transverse ridge not interrupted, cervical groove distinct, followed by 2 uninterrupted or minutely interrupted ridges, interspersed with 1 laterally interrupted or scale-like ridge and 1–2 short lateral ridges. Lateral margins clearly convex, with 7–8 spines: first anterolateral spine well-developed, exceeding lateral orbital spine, second spine (hepatic) minute, often obsolescent in males, slightly dorsomesially from lateral margin, and followed by 5–6 branchial spines behind distinct anterior cervical groove (3 anterior and 2–3 posterior). Rostrum leaf-like, horizontal, dorsally slightly or deeply concave, [1.5]1.6–1.9 × as long as broad, length 0.3–[0.5] and breadth 0.2–[0.3] that of carapace; lateral margins minutely serrated and convex, with well-developed supraocular and subapical spines. Pterygostomian flap ending in acute tooth; surface unarmed.

Thoracic sternum:As wide as long or slightly wider than long, lateral margins of posterior half slightly divergent. Sternite 3 moderately broad, [1.9]–2.4 × as wide as long, anterior margin convex. Sternite 4 widely contiguous to sternite 3; surface flattened, smooth; greatest width [2.8] –3.1 × that of sternite 3, 2.0–[2.3] × as wide as long.

Pleon: Elevated ridges upraised dorsally, with few short setae.Tergites 2–4 with anterior and posterior transverse elevated ridges; tergites 5–6 smooth.

Eye: Eyestalk length about 1.0 × broader than long, peduncle distally setose, not distinctly expanded proximally, with few short transverse striae on lateral surfaces; maximum corneal diameter 0.9–[1.0] × rostrum width, as wide as eyestalk.

Antennule: Article 1 longer than wide, with 3–4 distal spines: distomesial spine small or obsolescent; proximal lateral spine absent.

Antenna: Article 1 with prominent mesial process distally not reaching lateral antennular spine. Article 2 often with minute distal spines laterally and mesially. Articles 3 and 4 unarmed.

Mxp3: Ischium with distinct distal spines on flexor and extensor margin. Merus 0.6 × length of ischium, with 1 well-developed distal spine on extensor margin and 2 spines, subequal in size, on flexor margin.

P1: [2.4]2.0– 2.7 × carapace length (males), 1.3 (females), subcylindrical, with scattered spines and long stiff setae; merus and carpus with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus [0.9]0.5–1.0 length of carapace, [1.6]1.5–2.1 × as long as carpus. Carpus 1.1– [1.9] × as long as wide. Palm [0.9]0.7–1.0 × carpus length, 1.1–[1.4] × as long as broad with scattered small spines on dorsal and ventral surfaces, lateral and mesial margin irregular, with 1 small spine on distal mesial margin. Fingers unarmed, [0.9]–1.3 × palm length.

P2–4 (P2–3 absent from holotype): Moderately stout, setose and few spinose. Meri successively shorter posteriorly: P3 merus 0.9 × length of P2 merus, P4 merus 0.7–0.8 × length of P3 merus. P2 merus, 1.7–2.4 × carapace length, 3.8–4.0 × as long as broad, 1.2 × as long as P2 propodus; P3 merus 3.6–4.0 × as long as broad, 1.1–1.2 × as long as P3 propodus; P4 merus 2.7–2.8 × as long as broad, as long as P4 propodus; extensor margins of P2 and P3 with row of few small spines, proximally diminishing, with well-developed distal spine; P4 extensor margin irregular but unarmed, distal spine absent; flexor margins of all legs irregular, with distal spine on P2–3, distal spine absent in P4. Carpi with 1 spine on extensor margins on P2–3, unarmed on P4; distal spine prominent on P2–3, absent on P4; row of small spines below extensor margins on lateral surface of P2–3, unarmed on P4. Propodi stout, 4.0–5.0 × as long as broad; extensor margins irregular, usually unarmed; flexor margins with 5–6 slender movable spines in addition to distal pair. Dactyli 0.7–0.8 × length of propodi, ending in incurved, strong, sharp spine; flexor margins with 5–6 well-developed dactylar spines, each with 1 spinule.

Eggs: Ov. F carried approximately 8– 30 eggs of 0.3–0.4 mm diameter.

Live colour. Body orange, with dark orange-reddish patches. P1 pale yellow, with dark orange-brownish bands. P2–4 pale yellow, with dark orange bands.

Genetic data. COI and 16S, Table 1.

Distribution. Papua New Guinea, between 1 and 37 m.

Remarks. Phylladiorhynchus phanus belongs to the group of species having the epigastric ridge unarmed, the carapace and pleon ridges elevated, upraised, and dactylar spines on the flexor margins of the P2-4 dactyli. The new species is closely related to P. marina from Vanuatu. Both species are highly similar, and very difficult to distinguish using morphological characters only, therefore they are considered cryptic species. Both species might be distinguished on the basis of their different coloration (the base color of the carapace is orange in P. phanus , whereas the overall colour pattern is brownish in P. marina , compare Figures 55B and 55H View FIGURE 55 ), however, we can’t discount intraspecific variability and this character might not be reliable. There are some scattered long plumose setae on the carapace ridges of P. marina , whereas these setae are always absent in P. phanus . On the other hand, the setae can be missing in preserved specimens. P. phanus is also close to P. phlias , from Papua New Guinea (see the differences under the Remarks of this species).

The genetic divergences between P. phanus and P. marina were 13% (COI) and 4% (16S). The two and three sequences of P. phanus from Papua New Guinea diverged 0.7% (COI) and 0.1% (16S). The specimens of P. phanus range in size from 0.9 to 2.5 mm postorbital carapace length.