Phylladiorhynchus butes, 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 : 29-32

Phylladiorhynchus butes n. sp.

( Figs. 9 , 11J )

Phylladiorhynchus ikedai . — Baba, 1991, 485, fig. 4a (in part, only specimens from MUSORSTOM 6, Stn CP401 [MNHN Ga- 2044]).

Records requiring verification:

Phylladiorhynchus ikedai . — Baba, 2005: 200, 304 (Key Islands).

Type material. Holotype. Indonesia, KARUBAR Stn DW 18, 05.3000°S, 133.0167°E, 205–212 m, 24 October 1991: M 3.0 mm (MNHN-IU-2014-13803).

Paratypes. Indonesia. KARUBAR Stn DW 18, 05.3000°S, 133.0167°E, 205–212 m, 25 October 1991: 1 F 2.7 mm (MNHN-IU-2019-2697) .

New Caledonia. MUSORSTOM 6 Stn CP 401, 20.7025°S, 167.0058°E, 270 m, 14 February 1989: 1 M 2.3 mm (MNHN-IU-2014-23834 (Ga-2044)) .

Chesterfield Islands . EBISCO Stn DW 2547, 21.1000°S, 158.6000°E, 356–438 m, 11 October 2005: 1 F 2.1 mm (MNHN-IU-2016-449) .

Other material. New Caledonia. KANADEEP Stn DW 5025, 20.3833°S, 158.6667°E, 350–420 m, 21 September 2017: 1 M 2.6 mm (MNHN-IU-2017-2754) .

EXBODI Stn CP3829, 22.0333°S, 167.0833°E, 350–360 m, 8 September 2011: 1 ov. F 2.4 mm (MNHN-IU- 2019-2694).

French Polynesia. TARASOC Stn DW 3503, 17.5667°S, 149.3000°W, 350 m, 25 October 2009: 2 ov. F 2.1–2.2 mm (MNHN-IU-2014-13735) .

Etymology. From the name Butes, an Argonaut, son of Coronus. The name is considered a substantive in apposition.

Description. Carapace: as long as or slightly longer than broad; transverse ridges with dense short setae. Gastric region flattened with 4 transverse ridges: epigastric ridge indistinct, with few plumose setae, with 4–5 spines (rarely with 1 median spine, usually with one median produced scale furnished with thick plumose setae, and 2 pairs of spines laterally); anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge not medially interrupted, or minutely interrupted, laterally interrupted by anterior branch of cervical groove, continuing uninterrupted to first branchial spine; anterior metagastric ridge scale-like. Mid-transverse ridge not interrupted, preceded by shallow or undistinct cervical groove, followed by 2 not interrupted or minutely interrupted ridges, interspersed with 1–2 short lateral ridges and sometimes few, short scattered scales. Lateral margins slightly convex, with 7 spines: first anterolateral spine well-developed, reaching or exceeding level of lateral orbital spine, second spine (hepatic) small, slightly dorsomesially from lateral margin, and followed by 5 branchial spines (3 anterior and 2 posterior). Rostrum leaf-like, horizontal, dorsally flattish or slightly concave, [1.6]1.5–1.8 × as long as broad, length [0.4]–0.5 and breadth 0.3 that of carapace; lateral margins smooth and slightly convex, with well-developed supraocular basal spines, subapical spines minute or absent. Pterygostomian flap with anterior small spine; upper margin smooth.

Thoracic sternum: As wide as or slightly longer than wide. Sternite 3 quadrangular, 1.2–[1.7] × as wide as long, anterior margin straight or slightly convex, moderately produced anterolaterally. Sternite 4 widely contiguous to sternite 3; surface not depressed in midline, smooth; greatest width 2.4–[3.0] × that of sternite 3, 1.7–[2.2] × as wide as long.

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

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

Antennule: Article 1 1.3 × longer than wide, with 5 spines: distomesial spine well-developed; proximal lateral spine small, always present.

Antenna: Article 1 with prominent mesial process, nearly reaching end of lateralmost antennular spine. Article 2 with distinct distal spines laterally and mesially. Article 3 with small distomesial spine. Article 4 unarmed.

Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus 0.5 × length of ischium with well-developed distal spine on extensor margin and 2 strong spines on flexor margin.

P1 (lost in holotype): 3.4–3.6 (males and females) × carapace length; slender, subcylindrical, spiny and with scattered long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus 1.3–1.4 length of carapace, 1.9–2 × as long as carpus. Carpus 3.1–3.3 × as long as wide. Palm 1.3–1.4 × carpus length, 3.0–3.6 × as long as broad. Fingers unarmed, 0.7–0.8 × palm length.

P2–4: Slender, subcylindrical, moderately setose and spinose. Meri successively shorter posteriorly: P3 merus 0.8 – [0.9] × length of P2 merus, P4 merus [0.8] – 0.9 × length of P3 merus. P2 merus, [0.8] – 0.9 × carapace length, [4.5] – 5.5 × as long as broad, 1.2 – [1.3] × as long as P2 propodus; P3 merus [4.5] – 5.0 × as long as broad, 1.1 – [1.3] × as long as P3 propodus; P4 merus [4.0] – 5.1 × as long as broad, [1.0] – 1.2 × 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, with small distal spine; flexor margins of P2–4 irregular, each with distal spine; P4 lateral surface with 1–2 small spines, absent in P2–3. Carpi with 3 or 4 spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–3, smaller on P4; row of small spines below extensor margin on lateral surface of P2–3, unarmed on P4; flexor margin unarmed. Propodi moderately slender, [5.5–6.0]5.5–7.5 × as long as broad; extensor margin irregular, usually armed with 2–4 small proximal spines on P2–3; flexor margin with 2–4 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 5–8 movable spines.

Eggs: Ov. F carried approximately 5– 15 eggs of 0.4–0.6 mm diameter.

Live colour. Unknown.

Genetic data. COI and 16S, Table 1.

Distribution. New Caledonia, Chesterfield Islands, Indonesia (Kei Islands), French Polynesia, from 205 to 438 m.

Remarks. Phylladiorhynchus butes belongs to the group of species having the epigastric ridge with 4 spines and often one median process or scale with thick plumose setae (rarely with 5 spines). The specimens range from 2.1 to 3.0 mm postorbital carapace length. Phylladiorhynchus butes resembles P. cepheus , from French Polynesia, and P. maestratii , from New Caledonia (see the differences under the Remarks of P. maestratii ). The three sequences of P. butes from French Polynesia, Indonesia and New Caledonia diverged 0.3% for COI and 0.3% for 16S.

Figures

FIGURE 9. Phylladiorhynchus butes n. sp., A–D, F–I, holotype male 3.0 mm (MNHN-IU-2014-13803); E, paratype female 2.1 mm (MNHN-IU-2016-449): A, carapace and pleon, dorsal view. B, thoracic sternites 3 and 4. C, left cephalic region, showing antennular and antennal peduncles, ventral view. D, right Mxp3, lateral view. E, left P1, dorsal view. F, left P2, lateral view. G, left P3, lateral view. H, left P4, lateral view. I, dactylus of left 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.