Phylladiorhynchus orpheus, 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 : 96-99
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Phylladiorhynchus orpheus n. sp.
Paratypes. French Polynesia. Marquesas Islands. PAKAIHI I TE MOANA Stn MQ 2-GR-B, 8°56.231’S, 140°07.240’W, 20–23 m, January 2012: 1 M broken (MHNH-IU-2014-13730) GoogleMaps .
French Polynesia. Society Islands. Moorea Island . 17.5145°S, 149.7616°W, 20 m, 23 October 2008: 1 M 2.1 mm ( UF36172 ) GoogleMaps .— 17.4764°S, 149.8316°W, 13 m, 31 January 2012: 1 M 2.0 mm ( UF33772 ) GoogleMaps , 1 M 2.7 mm ( UF33773 ) .— 17.4759°S, 149.8419°W, 13 m, 3 February 2012: 1 F 1.9 mm ( UF33866 ) GoogleMaps , 1 M 1.6 mm, 1 F 2.4 mm ( UF33867 ) , 1 ov. F 2.2 mm ( UF33961 ) , 4 M 1.1–1.9 mm, 6 ov. F 1.8–2.0 mm ( UF33962 ) .
Other material. French Polynesia. Society Islands. Moorea Island . 17.4764°S, 149.8316°W, 13 m, 6 February 2012: 6 M 1.4–2.0 mm, 5 ov. F 1.6–2.0 mm, 1 F 2.2 mm ( UF34088 ) GoogleMaps .— 17.4785°S, 149.8477°W, 13 m, 7 February 2012: 1 M 2.0 mm, 4 ov. F 1.6–2.3 mm, 1 F 1.7 mm ( UF34158 ) GoogleMaps .— 17.4785°S, 149.8477°W, 13 m, 8 February 2012: 1 ov. F 2.6 mm ( UF34209 ) GoogleMaps .— BENTHAUS Stn DW1968, 23°23’S, 150°44’W, 100–120 m, 20 November 2002: 1 M 2.3 mm (MNHN-IU-2019-2633) GoogleMaps .
Northern Mariana Islands. Saipan Island. Stn SAI-435, 15.0978°N, 145.7434°E, 17m, 11 April 2014: 1 ov.F 2.0 mm ( UF54495 ) GoogleMaps .— Stn SAI-640, 15.15620°N, 145.6899°E, 11 m, 17 April 2014: 4 M 1.3–2.0 mm, 1 F 2.3 mm ( UF54489 ) GoogleMaps .— Stn SAI-788, 15.15620417°N, 145.6899585°E, 11 m, 17 April 2014: 1 M 1.4 mM 1 F 2.0 mm ( UF54502 ) GoogleMaps .— Stn SAI-947, 15.27406°N, 145.79106°E, 9 m, 18 April 2014: 2 M 1.6–2.0 mm, 1 ov. F 1.8 mm ( UF54498 ) GoogleMaps .— Pagan Island . Stn PAG-404, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 2 M 1.3–2.3 mm ( UF54491 ) GoogleMaps .— Stn PAG-409, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 1 F 1.9 mm ( UF54488 ) GoogleMaps .— Stn PAG- 478, 18.1073°N, 145.7858°E, 11 m, 20 April 2014: 1 M 1.5 mm, 1 ov. F 2.0 mm ( UF54486 ) GoogleMaps .— Stn PAG-695, 18.0706°N, 145.7137°E, 11 m, 20 April 2014: 1 M 2.0 mm, 1 ov. F 1.9 mm ( UF54499 ) GoogleMaps .— Stn PAG-696, 18.0706°N, 145.7137°E, 11 m, 20 April 2014: 2 ov. F 2.1–2.4 mm ( UF54500 ) GoogleMaps .— Stn PAG-1149, 18.0706°N, 145.7137°E, 11 m, 20 April 2014: 1 M 1.9 mm ( UF54497 ) GoogleMaps .— Stn PAG-839, 18.11947°N, 145.7555°E, 12 m, 23 April 2014: 1 M 1.5 mm, 2 ov. F 1.6–1.8 mm ( UF54487 ) GoogleMaps .— Stn PAG-898, 18.11947°N, 145.7555°E, 12 m, 23 April 2014: 3 M 1.5–2.4 mm 2 ov. F 2.0– 2.3 mm ( UF54485 ) GoogleMaps .— Maug Islands . Stn MAU-475, 20.0141°N, 145.2342°E, 15 m, 03 May 2014: 1 M 1.6 mm ( UF54490 ) GoogleMaps .
Mariana Islands. Guam Island. Stn GUA-645, 13.57847°N, 144.82831°E, 11 m, 25 March 2014: 1 M 1.3 mm, 1ov. F 1.8 mm ( UF54542 ) GoogleMaps .— Stn GUA-688, 13.57847°N, 144.82831°E, 11 m, 25 March 2014: 1 ov. F 2.4 mm ( UF54496 ) GoogleMaps .
American Samoa. Rose Atoll. Stn ROS-777, 14.5293°S, 168.1534°W, 10 m, 16 March 2015: 1 F 1.2 mm ( UF54493 ) GoogleMaps .— Stn ROS-689, 14.5596°S, 168.1601°W, 45 m, 18 March 2015: 1 M 1.2 mm ( UF54492 ) GoogleMaps .— Tutuila Island . Stn TUT 138, 14.3604°S, 170.7502°W, 17 m, 26 February 2015: 1 F 2.1 mm ( UF54494 ) GoogleMaps .
Kiribati. Line islands, Millenium Island . 9.91°S, 150.21°W, 12 m, 5 November 2013: 1 ov. F 2.0 mm, in dead Pocillopora ( UF39269 ) GoogleMaps .— Jarvis Island. Stn JAR-653, 0.36900°S, 160.0081°W, 16 m, 10 April 2015: 1 M 1.8 mm ( UF54501 ) GoogleMaps .
Papua New Guinea. PAPUA NIUGINI Stn PB 07, 05.1800°S, 145.8300°E, 22 m, 30 December 2012: 1 M 2.0 mm (MNHN-IU-2013-397).—KAVIENG Stn KB 28, 02.7283°S, 150.6400°E, 15–26 m, 11 June 2014: 1 M 1.7 mm (MNHN-IU-2014-13657) GoogleMaps .
Etymology. From the name Orpheus, an Argonaut, son of Calliope and Oeagrus. The name is considered a substantive in apposition.
Description. Carapace: [1.1]–1.2 longer than broad; transverse ridges with a few short setae. Gastric region flattened with 4 transverse ridges (usually barely distinct): epigastric ridge with 2 median spines; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge not medially interrupted, laterally continuing to first branchial spine, followed by some short lateral scales; anterior metagastric ridge scale-like, often followed by a short scale. Mid-transverse ridge not interrupted, medially depressed, preceded by cervical groove distinct, followed by 2 not interrupted or minutely interrupted ridges, interspersed with 1 short lateral ridge and sometimes few, short scattered scales. Lateral margins straight or slightly convex, with 4 distinct spines: first anterolateral spine well-developed, reaching anteriorly to level of lateral orbital spine, hepatic margin unarmed; anterolateral spine followed by 3 branchial spines (2 anterior and 1 posterior). Rostrum leaf-like, horizontal, dorsally concave, [1.5]1.4–1.6 × as long as broad, length 0.3–[0.4] and breadth 0.2–[0.3] that of carapace; lateral margins serrated and convex, with well-developed supraocular spines, and small subapical spines. Pterygostomian flap ending in acute tooth, upper margin smooth.
Thoracic sternum: As wide as long. Sternite 3 moderately broad, [1.8]–2.0 × as wide as long, anterior margin convex, with blunted median projection, lateral margins rounded. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width 3.0 × that of sternite 3, 2.6–[2.7] × as wide as long.
Pleon: Elevated ridges with a few scattered short setae. Tergite 2 with anterior and posterior transverse elevated ridges with short setae and a few scattered long setae; tergites 3–4 with anterior transverse ridge; tergites 5–6 smooth.
Eye: Eyestalk length about [1.0]–1.1 × broader than long, peduncle distally setose, slightly expanded proximally; maximum corneal diameter 0.8–[0.9] × rostrum width, as wide as eyestalk.
Antennule: Article 1 slightly longer than wide, with 5 distal spines: distomesial spine well-developed; proximal lateral spine small, always present.
Antenna: Article 1 with prominent mesial process distally not reaching lateralmost antennular spine. Article 2 with well-developed distomesial and distolateral spines. Article 3 with distomesial spine. Article 4 unarmed.
Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus [0.7]0.7× length of ischium, with well-developed distal spine on extensor and flexor margins.
P1: 1.9–2.3 (males), 1.8–[1.9] (females) × carapace length; subcylindrical, spiny and with dense long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus 0.6–0.7 length of carapace, 1.3–1.9 × as long as carpus. Carpus 1.3–1.7 × as long as wide. Palm 1.1 × carpus length, 1.1–1.4 × as long as broad. Fingers [0.9]–1.1 × palm length; fixed finger unarmed; movable finger with basal spine.
P2–4: Stout, moderately setose and spinose. Meri successively shorter posteriorly: P3 merus 0.9 × length of P2 merus, P4 merus [0.8]–0.9 × length of P3 merus. P2 merus, [0.5]–0.6 × carapace length, 4.6–[4.7] × as long as broad, [1.1]–1.2 × as long as P2 propodus; P3 merus [4.5]4.4–4.7 × as long as broad, [1.1]–1.3 × as long as P3 propodus; P4 merus [3.4]3.2–3.6 × as long as broad, [1.0]–1.1 × as long as P4 propodus; extensor margin of P2–3 with row of spines, proximally diminishing, with prominent distal spine; P4 extensor margin irregular, unarmed; flexor margin irregular,with distal spine on P2–4. Carpi extensor margin unarmed on P2–4; distal spine prominent on P2–3, smaller on P4; extensor margin on lateral surface of P2–4 unarmed; flexor margin unarmed. Propodi stout, [4.7]4.5–5.0 × as long as broad; extensor margin unarmed; flexor margin with 3–4 slender movable spines in addition to distal pair. Dactyli [0.6]–0.8 × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 4–5 movable spines.
Eggs: Ov. F carried approximately 5– 20 eggs of 0.3–0.5 mm diameter.
Live colour. Body orange, with dark orange spots and often with blue-purple patches and bands. P1 whitish, with brownish stripes. P2–4 whitish, with brown transverse stripes.
Genetic data. COI and 16S, Table 1.
Distribution. Papua New Guinea, Northern Mariana Islands, Guam Island, American Samoa (Rose Atoll), Kiribati, New Caledonia and French Polynesia from 8 to 120 m.
Remarks. Phylladiorhynchus orpheus belongs to the group of species with 2 median epigastric spies, without hepatic spine and 2 spines on the anterior branchial margin. Phylladiorhynchus orpheus is closely related to P. lynceus , from Chagos, Western Australia, Kiribati and Samoa, P. priasus , from Mariana and Marshall Islands, and P. integrirostris from Hawaii. However, the new species can be easily distinguished from these species by the following differences:
- The rostral margins are usually smooth in P. orpheus , whereas these margins are always serrated in the other species.
- The carapace ridges are flattened and often indistinct in P. orpheus , whereas these ridges are elevated and distinct in the other species.
- The metagastric ridge is scale-like in P. orpheus , whereas this ridge is medially interrupted in the other species.
- The extensor margins of P2–4 propodi are unarmed in P. orpheus , whereas these margins are armed with 1–3 proximal spines in the other species.
The specimens of P. orpheus from Kiribati, Phoenix Islands, and from Papua New Guinea have the thoracic sternite 3 with a different shape. Furthermore, they have a different colour pattern. A revision of additional material from both localities, including genetic data, will be necessary to clarify if these small differences are intraspecific variations. The genetic divergences between P. orpheus and the other closely related species were very high: 19–22% (COI) and 13–16% (16S). The six sequences of P. orpheus from French Polynesia and Northern Mariana Islands diverged up to 2% for COI. The specimens of P. orpheus range from 1.1 to 2.7 mm postorbital carapace length.
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