Phylladiorhynchus peneleos, 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 : 102-104

Phylladiorhynchus peneleos n. sp.

( Figs. 39 , 55F )

Type material. Holotype. French Polynesia, Rapa. Stn 28, 27.6400°S, 144.3433°W, 30 m, 15 November 2002: ov. F 2.8 mm (MNHN-IU-2014-13734).

Paratypes. French Polynesia. Society Islands , Moorea. Off E Opunohu pass, at Shark Feeding buoy, outer reef slope from within rubble, 17.4817°S, 149.8558°W, 17–18 m, 16 October 2008: 1 F 3.0 mm ( UF15626 ) .— Between Temae and Afarealtu. Outer reef slope, 17.5145°S, 149.761°W, 20 m, 23 October 2008: 1 ov. F 2.2 mm ( UF36172 ) , 1, ov. F 2.4 mm ( UF16035 ) , 1 M 2.0 mm ( UF16078 ) .

Mariana Islands. Guam Island. Glass Breakwater. Near mouth of Apra harbour, among rocks, 3–6 m, 17 October 2001: 1 M 3.3 mm ( UF1224 ) .

Other material. New Caledonia. Exp. Mont. Komac, 12 m, 7 October 1993: 1 F 2.0 mm (MNHN- IU-2016- 468).

French Polynesia. Between Temae and Afarealtu. Outer reef slope, 17.4759°S, 149.8419°W, 11 m, 30 January 2012: 1 ov. F 2.1 mm ( UF34661 ) .

Etymology. From the name Peneleos, an Argonaut, son of Hippalmus and Asterope. 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 with 4 transverse ridges: epigastric ridge distinct, with 2 median spines (rarely with some outer small spine or granules), short scales laterally; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin, sometimes followed by a posterior protogatric ridge; anterior mesogastric ridge not medially interrupted, laterally continuing to first branchial spine, followed by some short lateral scales; anterior metagastric ridge not medially interrupted, followed by some short scales. Mid-transverse ridge not interrupted, medially depressed, cervical groove indistinct, followed by 2–3 not interrupted or minutely interrupted ridges, interspersed with 1 short lateral ridge and few short scales. Lateral margins nearly straight or slightly convex, with 5 distinct spines: first anterolateral spine well-developed, reaching anteriorly to level of lateral orbital spine, second spine (hepatic) small, slightly dorsomesially from lateral margin, and followed by 3 branchial spines (2 anterior and 1 posterior). Rostrum leaf-like, horizontal, dorsally flattish, 1.6–[1.7] × as long as broad, length 0.3–[0.4] and breadth 0.2 that of carapace; lateral margins serrated and convex, with well-developed supraocular spines, subapical spines absent. Pterygostomian flap ending in sharp tooth, upper margin smooth.

Thoracic sternum: As wide as long. Sternite 3 broad, 3.4–[4.0] × as wide as long, anterior margin serrated and convex, with a median projection, produced anterolaterally. Sternite 4 widely contiguous to sternite 3; anterolaterally serrated, surface depressed in midline, smooth; greatest width 1.3–[1.4] × that of sternite 3, [3.1]–3.2 × as wide as long.

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

Eye: Eyestalk length about [0.7]–0.8 × broader than long, peduncle distally setose, not distinctly expanded proximally; cornea expanded distally, maximum corneal diameter [1.0]–1.1 × rostrum width, 0.7–0.8 × maximum peduncle width.

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, nearly reaching end of proximal lateral antennular spine. Article 2 with well-developed distomesial and distolateral spines. Article 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 and flexor margins.

P1 (lost in holotype): 2.8–3.8 (males), 2.3–2.4 (females) × carapace length; subcylindrical, spiny and with long stiff setae and dense thick iridescent and plumose setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus 0.9–1.4 length of carapace. Carpus 1.7–1.9 × as long as wide. Palm 1.0–1.4 × carpus length, 2.0–2.5 × as long as broad. Fingers 0.6–1.0 × palm length; fixed finger with small basal spine; movable finger unarmed (large basal spine in 39F) fingers also extremely gaping.

P2–4: Slender, densely 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, 0.7–[0.8] × carapace length, [4.0]–5.0 × as long as broad, [1.2] 1.3 × as long as P2 propodus; P3 merus 3.8–4 × as long as broad, [1.0]–1.1 × as long as P3 propodus; P4 merus 3.6–[3.6] × 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, distal spine absent in P4. Carpi with 1–3 spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–3, smaller on P4; granules below extensor margin on lateral surface of P2–4; flexor margin unarmed. Propodi moderately slender, [5.0–5.8]4.9–6.0 × as long as broad; extensor margin irregular, armed with 2–4 spines on proximal half; flexor margin with 3–4 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 5–6 movable spines.

Eggs: Ov. F carried approximately 6– 20 eggs of 0.3–0.4 mm diameter.

Live colour. Body light orange, with dark orange-brownish small spots. P1 light orange, tip of fingers dark orange-reddish. P2–4 whitish, with dark orange-brownish bands.

Genetic data. COI and 16S, Table 1.

Distribution. Guam Island, French Polynesia and New Caledonia, between 3 and 30 m.

Remarks. Phylladiorhynchus peneleos belongs to the group of species having 2 median epigastric spines, the hepatic margin armed with 1 spine, and 2 spines on the anterior branchial margin. The new species is morphologically close to P. bahamut , from the Red Sea. However, they can be distinguished by the following characters:

- The gastric region has several secondary ridges in P. peneleos , whereas these ridges are absent in P. bahamut .

- The carapace ridges have some iridescent thick setae in P. bahamut , whereas these setae are in P. peneleos .

- Thoracic sternite 3 is broad, more than 3 × wider than long, in P. peneleos , whereas the sternite 3 is less than twice wider than long in P. bahamut .

- The cornea is wider than the stalk in P. peneleos , whereas it is 0.7–0.8 × width of the eyestalk in P. bahamut .

- The P1 has plumose setae in P. peneleos , whereas these setae are absent in P. bahamut .

The genetic divergences between P. peneleos and P. bahamut were very high 32% (COI) and 14% (16S). The four-six sequences of P. peneleos from French Polynesia diverged 0.15% for COI and 0% for 16S respectively. The specimens of P. peneleos range from 2.0 to 3.3 mm postorbital carapace length.

Figures

FIGURE 39. Phylladiorhynchus peneleos n. sp., A–D, G–I, holotype ovigerous female 2.8 mm (MNHN-IU-2014-13734); E- F, paratype male 3.3 mm (UF1224): 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, merus and carpus, dorsal view. F, left P1, propodus and dactylus, dorsal view. G, left P2, lateral view. H, right P3, lateral view. I, dactylus of right P3, lateral view. Scale bars: 1.0 mm.

FIGURE 55. Colour in life, dorsal view.A, Phylladiorhynchus lini n. sp. Taiwan, holotype female 2.2 mm (NMMBCD5596). B, Phylladiorhynchus marina n. sp. Vanuatu, ovigerous female 2.0 mm (MNHN-IU-2014-13887). C, Phylladiorhynchus medea n. sp. New Caledonia, female 1.9 mm (MNHN-IU-2014-20063). D, Phylladiorhynchus orpheus n. sp. French Polynesia, ovigerous female 2.0 mm (UF9732). E, Phylladiorhynchus paula n. sp. îles de Mayotte. des Glorieuses et des Comores, female 3.3 mm (MNHN-IU-2016-7003). F, Phylladiorhynchus peneleos n. sp. French Polynesia, male 2.0 mm (UF16078). G, Phylladiorhynhus pepei n. sp. Madagascar, male 3.2 mm (MNHN-IU-2016-486). H, Phylladiorhynchus phanus n. sp. Papua New Guinea, ovigerous female 2.5 mm (MNHN-IU-2014-2893). I. Phylladiorhynchus phlias n. sp. Papua New Guinea, ovigerous female 1.3 mm (MNHN-IU-2013-703).