Phylladiorhynchus heptacanthus 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 heptacanthus

description: <i>Phylladiorhynchus heptacanthus</i> n. sp. (Figs. 15, 21C) <b>Type material</b>. <i>Holotype</i>. Chesterfield Islands. KANADEEP Stn DW 4960, 23.0667°S, 159.4667°E, 310 m, 6 September 2017: F 2.1 mm (MNHN-IU-2017-2534). <i>Paratypes</i>. Chesterfield Islands. EBISCO no Stn details: 1 ov. F 1.8 mm (MNHN-IU-2014-13851). KANADEEP Stn DW 4950, 24.0833°S, 159.7000°E, 330–500 m, 5 September 2017: 1 M 2.2 mm (MNHN-IU-2017-2515).— Stn CP 4953, 24.1667°S, 159.6833°E, 270–320 m, 5 September 2017: 4 M 1.0– 1.4 mm, 2 ov. F 1.6–1.8 mm, 6 F 1.4–1.8 mm (MNHN-IU-2017-3326). <b>Other material</b>. Chesterfield Islands. KANADEEP Stn DW 4961, 23.0333°S, 159.4666°E, 300–430 m, 6 September 2017: 1 F 2.2 mm (MNHN-IU-2017-2729). New Caledonia. KANACONO Stn CP 4673, 22.7833°S, 167.4500°E, 244–285 m, 13 August 2016: 1 ov. F 1.9 mm (MNHN-IU-2017-11724). <b>Etymology</b>. From the Greek <i>hepta</i>, seven, and <i>akantha,</i> spine, in reference to the seven spines on the dorsal surface of the carapace. <b>Description.</b> <i>Carapace:</i> Robust or massive, [0.8]–0.9 × as long as broad; transverse ridges elevated, serrated, with few short setae, and few scattered long thick iridescent setae. Gastric region convex (upraised dorsally) with transverse scale-like ridges: epigastric ridge indistinct, with 5 spines (1 median and and 2 pairs of spines laterally), followed by 1 scale behind median epigastric spine; anterior protogastric ridge undistinct or scale like, not continuing laterally to carapace margin, armed with 1 parahepatic spine on each side, behind lateralmost epigastric spines, posterior protogastric area scale-like; anterior mesogastric ridge indistinct with some scales or scale-like, laterally continuing with few scales, posterior mesogastric ridge scale-like; anterior metagastric ridge scale-like, followed by small scale(s) on posterior metagastric region. Mid-transverse ridge not interrupted, medially depressed, serrated laterally, preceded by distinct cervical groove, followed by 2uninterrupted or minutely interrupted ridges, interspersed with 1 short lateral ridge and some scales. Lateral margins clearly convex, with 7 spines: first anterolateral spine well-developed, not reaching anteriorly end of strong lateral orbital spine, second spine (hepatic) well-developed, and followed by 5 branchial spines (3 anterior and 2 posterior). Rostrum leaf-like to subtriangular, dorsally sharply concave in anteroposterior midline, [1.1]1.0–3.0 × as long as broad, length [0.4]–0.4 and breadth [0.3]0.3 that of carapace; lateral margins serrated and convex, with small supraocular basal spines, subapical spines absent. Pterygostomian flap ending in anterior spine, upper margin smooth, with series of uprised ridges. <i>Thoracic sternum</i>: 0.9 × as long as wide. Sternite 3 moderately broad, [2.4]–2.6 × as wide as long, anterior margin straight, or slightly convex. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width 2.6–[2.7] × that of sternite 3, 2.5 × as wide as long. <i>Pleon</i>: Elevated ridges upraised dorsally, with a few scattered short setae. Tergites 2–3 with anterior and posterior transverse elevated ridges; tergite 4 with anterior transverse ridge; tergites 5–6 smooth. <i>Eye:</i> Eyestalk length about [1.5]1.3–1.6 × broader than long, peduncle distally setose, not distinctly expanded proximally; maximum corneal diameter [0.5]–0.6 × rostrum width, narrower than eyestalk. <i>Antennule</i>: Article 1 1.4 longer than wide, with 5 spines, distomesial spine well-developed, proximal lateral spine small. <i>Antenna:</i> Article 1 with prominent mesial process, distally falling well short of lateralmost antennular spine. Article 2 with small distal spines laterally and mesially. Article 3 with minute or distinct distomesial and distolateral spines. Article 4 unarmed. <i>Mxp3:</i> Ischium with distinct distal spines on flexor and extensor margins. Merus [0.5] × length of ischium at midlength, with 0–[1] distal spine on extensor margin and 2 spines on flexor margin. <i>P1:</i> [2.2] (female) (lost in most specimens) × carapace length; subcylindrical, spiny and with scattered long stiff setae and scattered plumose 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. Carpus [1.9]–2.0 × as long as wide. Palm 1.2–[1.3] × carpus length, [2.3] × as long as broad. Fingers unarmed, [0.7]–0.8 × palm length. <i>P2–4:</i> (lost in most specimens) Stout, subcylindrical, moderately setose and spinose. Meri successively shorter posteriorly: P3 merus [0.8] × length of P2 merus, P4 merus [0.8] × length of P3 merus. P2 merus, 0.6 × carapace length, 4.4 × as long as broad, [0.9] × as long as P2 propodus; P3 merus [5] × as long as broad, [1.2] × as long as P3 propodus; P4 merus [4.6] × as long as broad, [0.9] × as long as P4 propodus; extensor margin of P2–P3 with row of spines, proximally diminishing, with prominent distal spine; P4 extensor margin with 2 spines, distal spine absent; flexor margins of P2–4 irregular,with distal spine; P2–4 lateral surface with short striae. Carpi with 1–2 spines on extensor margin on P2–3, gap between the marginal and the distal spine, serrated on P4; distal spine prominent on P2–4; P2–4 flexor margins irregular, with distal spine. Propodi moderately slender, [6.8]–7.0 × as long as broad, extensor margin irregular, flexor margin with 2–3 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 5–6 movable spines. <i>Eggs.</i> Ov. F carried approximately 5– 15 eggs of 0.5–0.6 mm diameter. <b>Colour.</b> After some months in ethanol: light orange with reddish spots and patches remaining in carapace, rostrum and pleon. <b>Genetic data.</b> COI, mini-barcode fragment (158 bp). <b>Distribution.</b> New Caledonia and Chesterfield Islands, depth 244– 500 m. <b>Remarks.</b> <i>Phylladiorhynchus heptacanthus</i> belongs to the group of species having 5 epigastric spines, 3 spines on the anterior branchial margin and a leaf-like rostrum. The closest species is <i>P. eneus</i>, from Indonesia, Philippines, Papua New Guinea and New Caledonia. However, <i>P. heptacanthus</i> is easily distinguished from this species by the presence of parahepatic spines, being absent in <i>P. eneus</i>. Furthermore, the rostrum supraocular basal spines are small in <i>P. heptacanthu</i> s, whereas they are well-developed in <i>P. eneus</i>. The specimens of <i>P. heptacanthus</i> range from 1.0 to 2.2 mm postorbital carapace length. The COI divergence (mini-barcode fragment) between <i>P. eneus</i> and <i>P. heptacanthus</i> was 22%.
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 44-45, DOI: 10.11646/zootaxa.5008.1.1, http://zenodo.org/record/5157455