Phylladiorhynchus boucheti, 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 : 27-29

Phylladiorhynchus boucheti n. sp.

( Figs. 8 , 11I )

Type material. Holotype. Chesterfield Islands . KANADEEP Stn DW 4969, 21.0000°S, 158.5000°E, 500–750 m, 8 September 2017: M 2.6 mm (MNHN-IU-2017-3816)

Paratypes. Chesterfield Islands . KANADEEP Stn DW 4969, 21.0000°S, 158.5000°E, 500–750 m, 8 September 2017: 1 M 3.0 mm (MNHN-IU-2019-2690).— Stn DW 4993, 4.2500°S, 166.9667°E, 560–610 m, 13 September 2017: 1 ov. F 2.5 mm (MNHN-IU-2017-3830)

Etymology. Named after Philippe Bouchet, head of conservation of the general mollusk collection of the Muséum national d’Histoire naturelle, Paris.

Description. Carapace: as long as or longer than broad ([1.0]–1.2 × as long as broad); transverse ridges with dense short setae, without long setae. Gastric region flattened, with 3 transverse ridges: epigastric ridge distinct with 4 spines; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge medially interrupted, laterally interrupted by cervical groove; anterior metagastric area with a few scales, otherwise absent. Mid-transverse ridge not interrupted, medially depressed, preceded by distinct cervical groove, followed by 2 not interrupted or minutely interrupted ridges, interspersed with 2 short lateral ridges and few, short scattered scales. Lateral margins straight or slightly convex, with 6–7 spines: first anterolateral spine welldeveloped, overreaching anteriorly level of lateral orbital spine, second spine (hepatic) well-developed, slightly dorsomesially from lateral margin, and followed by 4–5 branchial spines (3 anterior and 1–2 posterior). Rostrum subtriangular, horizontal, dorsally flattish or slightly concave, 0.8–[1.3] × as long as broad, length 0.2–[0.3] and breadth [0.3]0.3 that of carapace; lateral margins smooth and slightly concave, with well-developed supraocular basal spines, and minute subapical spines. Orbit sharply excavated. Pterygostomian flap ending in blunt tooth; upper margin smooth.

Thoracic sternum: As wide as long. Sternite 3 sharply broad, [3.5]–4.5 × as wide as long, anterior margin slightly concave, or straight, with median feeble excavation. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width 3.0 × that of sternite 3, 2.7–[2.9] × as wide as long.

Pleon: Elevated ridges with a few scattered short setae. Tergite 2 with anterior and posterior transverse elevated ridges; tergites 3–4 with anterior transverse ridge; tergites 5–6 smooth.

Eye: Eyestalk length as broad as long, peduncle distally setose, not distinctly expanded proximally; maximum corneal diameter 1.0–[1.1] × rostrum width, as wide as eyestalk.

Antennule: Article 1 1.5 × longer than wide, with 5 distal spines: distomesial spine well-developed; proximal lateral spine small.

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

Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus [0.6]–0.7 × length of ischium, with well-developed distal spine on extensor margin and 2 strong spines on flexor margin.

P1: [3.9] × carapace length (male), 2.9 (female); subcylindrical, spiny and with scattered long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, mesial spines usually stronger than others. Merus 1.2–[1.6] length of carapace, [2.1]–2.3 × as long as carpus. Carpus [2.7]–3.5 × as long as wide. Palm 1.1–[1.3] × carpus length, [2.6]–2.7 × as long as broad. Fingers [0.6]–0.8 × palm length; fixed finger unarmed; movable finger with basal spine.

P2–4: Slender, subcylindrical, moderately setose and spinose. Meri successively shorter posteriorly: P3 merus 0.7–[0.8] × length of P2 merus, P4 merus 0.8–[0.9] × length of P3 merus. P2 merus, 0.9 × carapace length, [7.2]7.0– 8.5 × as long as broad, [1.3]–1.4 × as long as P2 propodus; P3 merus [6.5]–9.0 × as long as broad, [1.1]–1.3 × as long as P3 propodus; P4 merus [5.4]5.0–7.1 × as long as broad, 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, distal spine absent; flexor margins of P2–3 irregular, with distal spine, absent in P4. Carpi with 1–2 spines on extensor margin on P2–3, distal spine prominent, unarmed on P4; row of small spines below extensor margin on lateral surface of P2–3. Propodi slender, [5.5–7.0]7.1–9.0 × as long as broad; extensor margin irregular, usually armed with distinct spine on proximal half of P2; flexor margin with 4 slender movable spines in addition to distal pair. Dactyli 0.5–[0.6] × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 7–10 movable spines.

Eggs: Ov. F (MNHN-IU-2017-3830) carried 25 eggs of 0.3–0.5 mm diameter.

Live colour. Unknown.

Genetic data. COI, Table 1.

Distribution. Chesterfield Islands, from 500 to 750 m.

Remarks. Phylladiorhynchus boucheti is characterized by the presence of a triangular rostrum, 4 epigastric spines, 3 spines on the anterior branchial margin of the carapace and Mxp3 merus with 2 spines on the flexor margin. The specimens range from 2.5 to 3.0 mm postorbital carapace length. Phylladiorhynchus boucheti closely resembles to P. iphiclus from French Polynesia and Vanuatu (see the differences under the Remarks of this species).

Figures

FIGURE 8. Phylladiorhynchus boucheti n. sp., holotype male 2.6 mm (MNHN-IU-2017-3816): A, carapace and pleon, dorsal view. B, thoracic sternites 3 and 4. C, left cephalic region, showing antennular and antennal peduncles, ventral view. D, left Mxp3, lateral view. E, right 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 bar: A, E-H = 1.0 mm; B–D, I = 0.6 mm.

FIGURE 11. Rostrum, dorsal view. A, Phylladiorhynchus acastus n. sp., paratype male 2.6 mm (MNHN-IU-2017-2646). B, P. amphion n. sp., holotype male 2.4 mm (WAM C55691). C, P. amphion n. sp., paratype female 2.6 mm (WAM C53887). D, P. argus n. sp., paratype ovigerous female 3.5 mm (MNHN-IU-2014-23836). E, P. asclepius n. sp., paratype ovigerous female 2.1 mm (UF22401). F, P. australis Schnabel & Ahyong, 2019, female 4.0 mm (MNHN-IU-2019-2596). G, P. bahamut n. sp., holotype male 2.5 mm (UF40205). H, P. barbeae n. sp., paratype male 2.2 mm (MNHN-IU-2019-2643). I, P. boucheti n. sp., paratype ovigerous female 2.5 mm (MNHN-IU-2017-3830). J, P. butes n. sp., paratype female 2.1 mm (MNHN-IU-2016-449). K, P. cepheus n. sp., paratype male 2.4 mm (MNHN-IU-2014-13858). L, P. eneus n. sp., paratype male 2.1 mm (MNHN-IU- 2014-13801). Scale bars = 1 mm.