Phylladiorhynchus lynceus Rodríguez-Flores &amp; Macpherson &amp; Machordom 2021, n. sp.
Creators: name: Rodríguez-Flores, Paula C.
name: Macpherson, Enrique
name: Machordom, Annie
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Galatheidae
Phylladiorhynchus
Phylladiorhynchus lynceus

description: <i>Phylladiorhynchus lynceus</i> n. sp. (Figs. 31, 33C, 37E–F) <b>Type material.</b> <i>Holotype.</i> Chagos Archipelago, Great Chagos Bank, Brothers Island. Stn CH 0614 dead branching coral heads. Outer Reef Slope, 8–12 m, February 2012: ov. F 2.0 mm (MNHN-IU-2019-2593) <i>Paratypes</i>. Chagos Archipelago, Great Chagos Bank, Eagle Island. Stn CH 1364 dead branching coral heads. Outer Reef Slope, 8–12 m, February 2012: 1 ov. F 1.4 mm, 1 F 1.3 mm (MNHN-IU-2019-2594).— Stn CH 0447, 1 M 1.7 mm (OUMNH. ZC.2014-09-064).— Stn CH 0230, 1 M 1.2 mm (OUMNH. ZC.2014-09-065). Kiribati. Line Islands. 9.91°S, 150.21°W, 11 m, 8 November 2013: 1 M 1.9 mm (UF41803).— Millenium island. 9.91°S, 150.21°W, 12 m, 5 November 2013: 1 M 1.8 mm 1 ov. F 1.3 mm (UF40895). <b>Other material</b>. American Samoa, Olosega Island. Stn OLO-187, 14.18140174°S, 169.6267462°W, 14 m, 14 March 2015: 1 M 1.8 mm (UF54480).— Stn OLO-094, 14.18140174°S, 169.6267462°W, 14 m, 14 March 2015: 1 ov. F 2.1 mm (UF54481).— Rose Atoll. Stn ROS-610, 14.54895°S, 168.13792°W, 15 m, 17 March 2015: 8 M 1.4– 2.1 mm, 8 ov. F 1.5–2.3 mm (UF54482).— Stn ROS-527, 14.54895°S, 168.13792°W, 15 m, 17 March 2015: 1 M 1.9 mm, 1 ov. F 1.8 mm (UF54483).— Stn ROS-562, 14.54895°S, 168.13792°W, 15 m, 17 March 2015: 10 M 1.4–2.1 mm, 13 ov. F 1.4–2.1 mm, 2 F 1.5–1.8 mm (UF54484).— Ofu Island. Stn OFU-121, 14.17765914°S, 169.649504°W, 14 m, 21 March 2015: 1 ov. F 2.3 mm (UF54477).— Stn OFU-168, 14.17765914°S, 169.649504°W, 14 m, 21 March 2015: 1 M 1.9 mm, 1 ov. F, 2.2 mm (UF54478).— Stn OFU-280, 14.18628°S, 169.6599°W, 14 m, 26 March 2015: 1 M 1.8 mm, 1 ov. F 1.9 mm (UF54479). Kiribati. Phoenix islands, Orona island. 4.519°S 172.227°W, 12 m, 17 September 2015: 1 ov. F 1.7 mm (UF51296).— 4.520°S, 172.230°W, 15 m, 18 September 2015: 1 M 1.5 mm (UF51370), 2 M 1.8–1.9 mm 1 ov. F 1.8 mm (UF51363).— Nikumaroro Island. 4.656°S, 174.545°W, 14 m, 23 September 2015: 1 ov. F 1.7 mm (UF51559).— 4.694° S 174.490°E, 7.5–9 m, 25 September 2015: 1 M 1.3 mm (UF51644). Western Australia. Hibernia Reef. Stn 142/K13, 11°59.292’S, 123°21.154’E, no depth, 4 October 2013: 1 M 2.1 mm (WAM C55689).— Rowley Shoals. Mermaid Reef. Stn 178/K14-T1, 17°09.69’S, 119°38.826’E, 12–18 m, 13 October 2014: 1 ov. F 1.6 mm (WAM C53889). <b>Etymology.</b> From the name <i>Lynceus</i>, an Argonaut, son of Aphareus and Arene. The name is considered a substantive in apposition. <b>Description.</b> <i>Carapace:</i> As long as or slightly longer than broad; transverse ridges with dense short setae and few scattered long and thick iridiscent setae. Gastric region slightly convex with 4 transverse ridges: epigastric ridge distinct with 2 spines (Samoa and Kiribati specimens often with 1 median produced scale usually with thick plumose setae before epigastric ridge), short scales laterally; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge not medially interrupted, laterally continuing to first branchial spine; sometimes followed by some short small scales; anterior metagastric ridge medially interrupted, laterally continuing to second branchial spine. Mid-transverse ridge not interrupted, cervical groove indistinct, followed by 2 not interrupted or minutely interrupted ridges, interspersed with 1 short lateral ridge and sometimes few, short scattered scales. Lateral margins slightly convex, with 4 distinct spines: first anterolateral spine welldeveloped, reaching anteriorly to level of lateral orbital spine, hepatic margin unarmed; anterolateral spine followed by 3 branchial spines (2 anterior and 1 posterior spines). Rostrum leaf-like, horizontal, dorsally concave, [1.5]–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 basal spines and small subapical spines. Pterygostomian flap ending in blunt tooth, upper margin smooth. <i>Thoracic sternum</i>: As wide as long. Sternite 3 quadrangular, slightly wider than long (1.5 × as wide as long), anterior margin with median blunted projection, lateral margins rounded. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width 3.0 × that of sternite 3, [2.7]2.5–3.0 × as wide as long. <i>Pleon</i>: Elevated ridges with short setae and a few scattered long setae. Tergite 2 with anterior and posterior transverse elevated ridges; tergites 3–4 with anterior transverse ridge; tergites 5–6 smooth. <i>Eye:</i> Eyestalk length about 0.9–[1.0] × broader than long, peduncle distally setose, slightly expanded proximally; maximum corneal diameter 0.8–[0.9] × rostrum width, narrower than eyestalk (0.8 × maximum peduncle width). <i>Antennule</i>: Article 1 slightly longer than wide, with 5 distal spines: distomesial spine small; proximal lateral spine small, always present. <i>Antenna:</i> 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 with distomesial spine. Article 4 unarmed. <i>Mxp3:</i> Ischium with distinct distal spines on flexor and extensor margins. Merus 0.6–[0.8] × length of ischium, with distal spine on extensor and flexor margins. <i>P1</i>: 1.7–2.0 (males), 2.0 (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 0.7–0.8 length of carapace, 2.0–2.1 × as long as carpus. Carpus 1.2–1.3 × as long as wide. Palm 1.2–1.3 × carpus length, 1.5–1.7 × as long as broad. Fingers unarmed, 0.6–0.9 × palm length. <i>P2–4</i>: Stout, setose and spinose. Meri successively shorter posteriorly: P3 merus 0.7–[0.8] × length of P2 merus, P4 merus 0.8 × length of P3 merus. P2 merus, 0.7–[0.8] × carapace length, [3.6]–3.8 × as long as broad, [1.2]–1.3 × as long as P2 propodus; P3 merus 3.7 × as long as broad, [1.0]–1.1 × as long as P3 propodus; P4 merus [2.8]2.7–3.2 × as long as broad, [1.0]–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, unarmed on P4. Carpi with 1–3 prominent spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–3, smaller on P4; row of small spines or granules below extensor margin on lateral surface of P2–3, unarmed on P4; flexor margin unarmed. Propodi stout, [3.8]3.3–4.3 × as long as broad; extensor margin irregular, armed with 1–3 spines on proximal half or unarmed; flexor margin with 3–4 slender movable spines in addition to distal pair. Dactyli 0.7–[0.8] × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 4–6 movable spines. <i>Eggs</i>: Ov. F carried approximately 5– 25 eggs of 0.3–0.4 mm diameter. <b>Live colour.</b> Unknown. <b>Genetic data.</b> COI and 16S, Table 1. <b>Distribution.</b> Chagos Archipelago, Western Australia, Kiribati, American Samoa, between 7.5 and 18 m. <b>Remarks.</b> <i>Phylladiorhynchus lynceus</i> belongs to the group of species with 2 epigastric spines and 2 spines on the anterior branchial margin. The closest species are: <i>P. integrirostris</i>, from Hawaii and <i>P. priasus</i> from the Mariana and Marshall Islands. The three species are barely distinguishable morphologically, although they are genetically very different (see the differences under the Remarks of <i>P. priasus</i>). Furthermore, these three species are also close to <i>P. orpheus</i> (see the differences under the Remarks of <i>P. orpheus</i>). The specimens of <i>P. lynceus</i> range from 1.2 to 2.3 mm postorbital carapace length. The four and seven sequences of <i>P. lynceus</i> from American Samoa and Chagos and Kiribati diverged 1.0–2.3% (COI) and 0–1% (16S), respectively.
description: Published as part of <i>Rodríguez-Flores, Paula C., Macpherson, Enrique &amp; Machordom, Annie, 2021, Revision of the squat lobsters of the genus Phylladiorhynchus Baba, 1969 (Crustacea, Decapoda, Galatheidae) with the description of 41 new species, pp. 1-159 in Zootaxa 5008 (1)</i> on pages 83-85, DOI: 10.11646/zootaxa.5008.1.1, http://zenodo.org/record/5157455