Phylladiorhynchus priasus, 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 : 120-123

Phylladiorhynchus priasus n. sp.

( Figs. 37 C–D , 46 , 50E )

Type material. Holotype. Mariana Islands, Maug Islands , Stn MAU-385, 20.02973294°N, 145.2084746°E, 17 m, 04 May 2014: M 2.2 mm ( UF54423 ).

Paratypes: Northern Mariana Islands. Maug Islands. Stn MAU-302, 20.01416942°N, 145.2342278°E, 15 m, 03 May 2014: 4 M 1.4–1.8 mm, 3 ov. F 1.6–1.9 mm, 1 F 1.7 mm ( UF54435 ) .— Stn MAU-303, 20.01416942°N, 145.2342278°E, 15, 03 May 2014: 4 M 1.4–2.3 mm ( UF54431 ) .— Stn MAU-304, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 2 M 1.8–2.1 mm, 5 ov. F 1.8–2.2 mm ( UF54434 ) .— Stn MAU-305, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014:1 M 1.6 mm, 2 ov. F 1.8–2.1 mm ( UF54433 ) .

Other material. Northern Mariana Islands, Maug Islands. Stn MAU-354, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 1 M 1.4 mm, 4 ov. F 2.0– 2.3 mm ( UF54432 ) .— Stn MAU-355, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 1 M 2.4 mm, 1 ov. F 2.0 mm ( UF54424 ) , 1 M 2.1 mm ( UF54425 ) .— Stn MAU-357, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 8 M 1.3–2.2 mm, 11 ov. F 1.5–2.3 mm, 6 F 1.4–1.9 mm ( UF54430 ) .— Stn MAU-476, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 1 F 1.9 mm ( UF 4470 ) .— Stn MAU-478, 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 2 M 1.4–1.9 mm, 1 F 1.5 mm ( UF54429 ) .— Stn MAU-479 20.01416942°N, 145.2342278°E, 15 m, 3 May 2014: 1 M 1.8 mm 3 ov. F 1.8–2.4 mm ( UF54427 ) .— Stn MAU-383, 20.02973294°N, 145.2084746°E, 17 m, 4 May 2014: 4 M 1.4–1.9 mm, 4 ov. F 1.6–2.1 mm ( UF54428 ) .— Stn MAU- 384, 20.02973294°N, 145.2084746°E, 17 m, 04 May 2014: 1 M 2.1 mm, 4 ov. F 2.0– 2.4 mm ( UF54426 ) .— Stn MAU-385, 20.02973294°N, 145.2084746°E, 17 m, 04 May 2014: 4 M 2.1–2.8 mm, 5 ov. F 2.0– 2.1 mm, 1 F 1.9 mm ( UF54422 )

Northern Mariana Islands, Pagan Island. Stn PAG-407, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 1 M 1.3 mm, 2 ov. F 2.0– 2.1 mm ( UF54453 ) .— Stn PAG-480, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 1 ov. F 2.0 mm ( UF54450 ) .— Stn PAG-483 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 7 M 1.4 –2.4 mm, 3 ov. F 2.2–2.5 mm ( UF54471 ) .— Stn PAG-565, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 1 ov. F 2.2 mm ( UF54476 ) .— Stn PAG-566, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 2 M 1.8–2.3 mm, 1 ov. F 2.3 mm, 1 F 1.6 mm ( UF54472 ) .— Stn PAG-567, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 2 M 2.3–2.8 mm ( UF54473 ) .— Stn PAG-568, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 3 M 1.3–1.5 mm ( UF54452 ) .— Stn PAG-571, 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 1 F 1.8 mm ( UF54443 ) .— Stn PAG-573 18.10734°N, 145.78587°E, 11 m, 20 April 2014: 2 M 1.8–1.9 mm ( UF54449 ) .— Stn PAG-603, 18.10734°N, 145.78587°E, 11 m, 20 April 2014:1 ov. F 2.1 mm ( UF54438 ) .— Stn PAG-694, 18.0706862°N, 145.7137933°E, 11 m, 20 April 2014: 1 M 1.4 mm, 1 ov. F 2.1 mm ( UF54440 ) , 1 M 1.6 mm ( UF54441 ) .— Stn PAG-697, 18.0706862°N, 145.7137933°E, 11m, 20 April 2014: 1 M 1.8 mm, 1 ov. F 1.9 mm ( UF54448 ) .— Stn PAG-762, 18.0706862°N, 145.7137933°E, 11m, 20 April 2014: 1 M 1.7 mm, 1 ov. F 2.0 mm ( UF54439 ) .— Stn PAG-809, 18.0706862°N, 145.7137933°E, 11 m, 20 April 2014: 2 M 1.4–1.6 mm, 1 F 1.5 mm ( UF54446 ) .— Stn PAG-810, 18.0706862°N, 145.7137933°E, 11 m, 20 April 2014: 1 ov. F 1.8 mm ( UF54445 ) .— Stn PAG-840, 18.11947952°N, 145.7555622°E, 12 m, 23 April 2014: 2 M 2.0– 2.3 mm ( UF54447 ) .— Stn PAG-841 18.11947952°N, 145.7555622°E, 12 m, 23 April 2014: 1 M 2.0 mm, 1 ov. F 2.1 mm ( UF54437 ) .— Stn PAG-865, 18.11947952°N, 145.7555622°E, 12 m, 23 April 2014: 1 ov. F 1.8 mm ( UF54451 ) .— Stn PAG-896, 18.11947952°N, 145.7555622°E, 12 m, 23 April 2014: 2 M 1.8–1.9 mm, 1 ov. F 2.0 mm, 1 F 1.8 mm ( UF54442 ) .— Stn PAG-900, 18.11947952°N, 145.7555622°E, 12 m, 23 April 2014: 1 M 1.8 mm ( UF54436 ) .— Stn PAG-957, 18.11947952°N, 145.7555622°E, 12 m, 23 April 2014: 1 M 2.0 mm, 1 ov. F 1.7 mm, 2 F 1.6–2.0 mm ( UF54444 ) .

Mariana Islands, Guam Island. 13.5167°N, 144.8°E, 10–25 m, 27 June 2003: 1 ov. F 1.6 mm ( UF4173 ) .—Stn GUA-601, 13.57847°N, 144.82831°E, 11 m, 25 March 2014: 1 F 2.1 mm ( UF54455 ) .—Stn GUA-645, 13.57847°N, 144.82831°E, 11 m, 25 March 2014: 2 M1.6–2.0 mm ( UF54456 ) .—Stn GUA-695, 13.57847°N, 144.82831°E, 11 m, 25 March 2014: 1 ov. F 1.9 mm ( UF54454 ) .

Marshall Islands, Wake Island. 19°17.259’N, 166°36.782’E, 11.5–13.5 m, 18 November 2005: 1ov. F 2.0 mm ( UF8548 ) .— no position, 15–21 m, 24 March 2009: 1ov. F 1.8 mm ( UF36081 ) .—Stn WAK-083, 19.2917761°N, 166.6072896°E, 14 m, 17 March 2014: 1 ov. F 2.2 mm ( UF54468 ) .—Stn WAK-084, 19.2917761°N, 166.6072896°E, 14 m, 17 March 2014: 5 M 1.6–2.2 mm, 4 ov. F 1.8–2.2 mm ( UF54467 ) .—Stn WAK-084, 19.2917761°N, 166.6072896°E, 14 m, 17 March 2014: 1 M 2.3 mm ( UF54541 ) .—Stn WAK-114, 19.2917761°N, 166.6072896°E, 14 m, 17 March 2014: 1 M 2.2 mm ( UF54458 ) .—Stn WAK-117, 19.2917761°N, 166.6072896°E, 14 m, 17 March 2014: 1 ov. F 1.7 mm ( UF54474 ) .—Stn WAK-118, 19.2917761°N, 166.6072896°E, 14 m, 17 March 2014: 15 M 1.5–2.0 mm, 6 ov. F 1.8–2.1 mm ( UF54469 ) .—Stn WAK-152, 19.31627096°N, 166.5983406°E, 12 m, 16 March 2014: 5 M 1.9–2.3 mm, 4 ov. F 1.8–2.1 mm, 5 F 1.9–2.3 mm ( UF54466 ) .—Stn WAK-189, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 3 ov. F 2.0– 2.5 mm, 1 F 2.0 mm ( UF54460 ) .—Stn WAK-218, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 2 M 1.9–2.2 mm ( UF54459 ) .—Stn WAK-219, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 3 M 2.5–2.6 mm ( UF54462 ) .—Stn WAK-220, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 1 ov. F 2.0 mm ( UF 54457 ) .—Stn WAK-221, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 1 M 1.9 mm, 2 ov. F 1.9–2.0 mm ( UF54463 ) .—Stn WAK-222, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 5 M 1.4–2.2 mm, 8 ov. F 1.7–2.3 mm ( UF54461 ) .—Stn WAK-252, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 16 M 1.3–2.3 mm, 21 ov. F 1.6–2.5 mm ( UF54475 ) .—Stn WAK-256, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 2 M 2.0– 2.1 mm, 2 ov. F 1.8–2.1 mm, 1 F 1.7 mm ( UF54465 ) .—Stn WAK-280, 19.27067533°N, 166.6516393°E, 14 m, 19 March 2014: 6 M 1.6–2.3 mm, 9 ov. F 1.5–2.2 mm, 1 F 1.7 mm ( UF4464 ) .

Etymology. From the name Priasus, an Argonaut, son of Caeneus and Phocus. The name is considered a substantive in apposition.

Description. Carapace: Slightly longer than broad; transverse ridges with dense short setae and few scattered long and thick iridescent setae. Gastric region with 4 transverse ridges: epigastric ridge distinct with 2 median spines, usually 1 median produced scale usually with thick plumose setae before epigastric ridge; 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. Mid-transverse ridge not interrupted, cervical groove indistinct, followed by 2 uninterrupted 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 well-developed, reaching anteriorly to level of lateral orbital spine, hepatic margin unarmed; anterolateral spine followed by 3 branchial spines (2 anterior and 1 posterior). Rostrum bottle-shaped, horizontal, dorsally concave, [1.1]–1.4 × as long as broad, length [0.3]–0.4 and breadth 0.25–[0.3] that of carapace; lateral margins serrated, straight proximally and distally slightly convex, with well-developed supraocular basal spines and small subapical spines. Pterygostomian flap ending in blunt tooth, upper margin smooth.

Thoracic sternum: As wide as long. Sternite 3 quadrangular, slightly wider than long (1.5 × as wide as long), anterior margin with a median blunted projection, lateral margins rounded. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width [2.9]–3.3 × that of sternite 3, 2.1–[2.9] × as wide as long.

Pleon: 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.

Eye: Eyestalk length about [0.9] × broader than long, peduncle distally setose, slightly expanded proximally; maximum corneal diameter [0.6]–0.7 × rostrum width, as narrower than eyestalk (0.8–0.9 × 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 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.

Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus [0.7]0.6–0.8 × length of ischium, with well-developed distal spine on extensor and flexor margins.

P1: [2.2]–2.9 (males), 1.8–2.1 (females) × carapace length; subcylindrical, spiny and with dense long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, mesial spines usually stronger than others. Merus [0.8]–0.9 length of carapace, [2.2]1.8–2.3 × as long as carpus. Carpus [1.3]1.1–1.4 × as long as wide. Palm [1.2]–1.4 × carpus length, [1.3]–1.7 × as long as broad. Fingers 0.6–[1] × palm length; fixed finger with 1–2 basal spines; movable finger with 1 basal spine.

P2–4: Stout, setose and spinose. Meri successively shorter posteriorly: P3 merus [0.7]0.7 × length of P2 merus, P4 merus 0.8–[0.9] × length of P3 merus. P2 merus, 1.6 – [1.7] × carapace length, 3.8–[5.0] × as long as broad, 1.2–[1.4] × as long as P2 propodus; P3 merus 3.8–[4.2] × as long as broad, [1.1]–1.4 × as long as P3 propodus; P4 merus 3.3–[3.4] × 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 P2–4, P4 lateral surface with row of 2–4 spines. Carpi with 1–3 prominent spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–4; row of small spines or granules below extensor margin on lateral surface of P2–3, unarmed on P4; flexor margin unarmed. Propodi stout, [4.0–5.0]3.7–5.6 × as long as broad; extensor margins irregular, armed with 1–3 spines on proximal half or unarmed; flexor margins with 3–4 slender movable spines in addition to distal pair. Dactyli [0.5–0.7] 0.5–0.8 × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 5–6 movable spines.

Eggs: Ov. F carried approximately 10– 35 eggs of 0.3–0.5 mm diameter.

Live colour. Unknown.

Genetic data. COI and 16S, Table 1.

Distribution. Mariana Islands, Guam Island, Marshall Islands, Wake Island, between 10 and 25 m.

Remarks. Phylladiorhynchus priasus belongs to the group of species with 2 epigastric spines, hepatic margin unarmed and 2 spines on the anterior branchial margin. The closest species are P. integrirostris , from Hawaii, and P. lynceus , from Chagos, Western Australia, Kiribati and Samoa. The 3 species are barely distinguishable morphologicaly although they are clearly different genetically. However, these species can be distigushed by the following subtle traits:

- Phylladiorhynchus priasus and P. integrirostris usually have a median produced scale, behind epigastric ridge, usually with thick setae [not in the neotype neither in the material examined by Schnabel & Ahyong (2019)]. However, this scale is always absent in all specimens examined of P. lynceus .

- The rostrum is proximally straight (bottle-shaped) in P. priasus and P. integrirostris , whereas it is convex (leaf-like) in P. lynceus .

- The carapace has numerous thick iridescent setae in P. lynceus and P. priasus , whereas these setae are usually absent in P. integrirostris .

The genetic divergences between P. priasus and P. lynceus were 7% (COI) and 2% (16S). These divergences were larger between P. priasus and P. integrirostris , 23% (COI) and 12% (16S).

Phylladiorhynchus priasus is also close to P. orpheus (see the differences under the Remarks of P. orpheus ). The eight and six sequences of P. priasus from Northern Mariana Islands, Guam and Wake Island diverged 0.4% (COI) and 0.1% (16S). The specimens of P. priasus ) range from 1.3 to 2.8 mm postorbital carapace length.

Figures

FIGURE 37. A, C, E, Carapace, dorsal view; B, D, F, rostrum, dorsal view.A-B, Phylladiorhynchus integrirostris (Dana, 1852), male 2.0 mm (UF54544). C-D, Phylladiorhynchus priasus n. sp., paratype male 2.0 mm (UF54475). E-F, Phylladiorhynchus lynceus n. sp., paratype male 1.8 mm (UF54479). Scale bars: A, C, E = 1 mm; B, D, F = 0.5 mm.

FIGURE 46. Phylladiorhynchus priasus n. sp., A–D, G–H, holotype male 2.2 mm (UF54423); 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 bars: 1.0 mm.

FIGURE 50. Rostrum, dorsal view. A, Phylladiorhynchus phlias n. sp., paratype male 1.4 mm (MNHN-IU-2014-13881). B, P. poeas n. sp., paratype male 3.3 mm (MNHN-IU-2014-13737). C, P. pollux n. sp., holotype ovigerous female 3.5 mm (MNHN-IU-2014-13797). D, P. porteri n. sp., paratype female 2.4 mm (MNHN-IU-2014-23831). E, P. priasus n. sp., paratype ovigerous female 2.1 mm (UF54422). F, P. pulchrus n. sp., paratype male 1.8 mm (MNHN-IU-2019-2675). G, P. punctatus n. sp., paratype male 1.7 mm (MNHN-IU-2019-20101). H, P. serrirostris (Melin, 1939), paralectotype male 2.3 mm (UPSTY2531). I, P. spinosus Schnabel & Ahyong, 2019, male 3.3 mm (MNHN-IU-2016-492). J, P. talaus n. sp., paratype ovigerous female 2.4 mm (WAM C43997). K, P. tiphys n. sp., holotype male 2.4 mm (MNHN-IU-2014-13794). L, P. zetes n. sp., holotype male 2.1 mm (UF30059). Scale bars: 1 mm.