Phylladiorhynchus talaus, 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 : 134-136

Phylladiorhynchus talaus n. sp.

( Figs. 50J , 51 )

Type material. Holotype. Western Australia, Montilivet Island, Stn 117/K12, 14.2883°S, 125.2255°E, 0–11 m, 25 October 2012: 1 ov. F 1.9 mm ( WAM C51399).

Paratypes. Western Australia. Adele Island Stn 01/K09-adhoc, 15.5234°S, 123.2053°E, 0–20 m, 13 October 2009: 1 ov. F 2.4 mm ( WAM C43997) .— Stn 02/K09-adhoc, 15.5192°S, 123.1957°E, 0–14 m, 14 October 2009: 1 ov. F 1.8 mm ( WAM C43826) .— Ningaloo Reef. 22.7581°S, 113.6491°E, 13 m, 1 May 2009: 1 F 1.8 mm ( UF 217029) .— 22.6083°S 113.6249°E, 10 m, 1 May 2009: 1 M 2.1 mm ( UF22293 ) .

Other material. Indonesia. Rumphius Exp. II. 1975, NE coast Marsegu Is., on coral. 18 January 1975: 1 M 2.7 mm (MNHN-IU-2014-23832 (Ga-1154)).

Papua New Guinea. PAPUA NIUGINI Stn PB 39, 05.2650°S, 145.7850°E, 18–27 m, 6 December 2012: 1 M 2.1 mm (MNHN-IU-2019-2637).—KAVIENG Stn KB 36, 02.6466°S, 150.6400°E, 3–8 m, 13 June 2014: 1 M 2.3 mm, 1 F 2.2 mm (MNHN-IU-2014-13664).— Stn KB 58, 02.5683°S, 150.6250°E, 12 m, 22 June 2014: 1 F 2.5 mm (MNHN-IU-2016-5858).— Stn KB 60, 02.5416°S, 150.5883°E, 20 m, 23 June 2014: 1 F 1.8 mm (MNHN-IU-2016- 476) .

Etymology. From the name Talaus, an Argonaut, son of Bias and Pero. The name is considered a substantive in apposition.

Description. Carapace: As long as or slightly longer than broad; transverse ridges with dense short setae and few scattered long and thick iridescent setae. Gastric region slightly convex with 4 transverse ridges: epigastric ridge distinct with 2 median spines and some lateral short scales; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge not medially interrupted, laterally continuing to first branchial spine; anterior metagastric scale-like or medially and laterally minutely interrupted, sometimes followed by short scales. Mid-transverse ridge not interrupted, medially slightly depressed, cervical groove indistinct, followed by 2 not interrupted or minutely interrupted ridges, interspersed with 2 short lateral ridges and few short scales. Lateral margins convex slightly convex, with 7 distinct spines: first anterolateral spine welldeveloped, reaching anteriorly to 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 convex, [1.2]–1.3 × as long as broad, length [0.3]–0.4 and breadth 0.3 that of carapace; lateral margins smooth or minutely serrated and convex, with well-developed supraocular basal spines and small subapical spines (tridentiform). Pterygostomian flap with anterior spine, upper margin smooth.

Thoracic sternum:As wide as long. Sternite 3 quadrangular, 1.5–[1.7] × as wide as long, anterior margin convex, anterolaterally rounded. Sternite 4 widely contiguous to sternite 3; anterolaterally serrated, surface depressed in midline, smooth; greatest width [2.5]–3.3 × that of sternite 3, 3.3–[3.5] × 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; tergite 3–4 with anterior transverse ridge, posterior transverse ridge absent; tergites 5–6 smooth.

Eye: Eyestalk length about 0.9–[1.1] × broader than long, peduncle distally setose, not distinctly expanded proximally; cornea expanded distally, maximum corneal diameter [1.1]–1.2 × rostrum width, as wide as eyestalk.

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 short or overreaching lateral antennular spine. Article 2 with well-developed distomesial and distolateral spines. Articles 3 with small distomesial spine. Article 4 unarmed.

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

P1: 2.3 (males), [2.0]–2.5 (females) × carapace length; subcylindrical, spiny and with long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus [0.8]0.6–0.9 length of carapace, [1.9]1.6–2.1 × as long as carpus. Carpus [1.6]1.5–1.9 × as long as wide. Palm [1.1]–1.3 × carpus length, [1.5]–2.3 × as long as broad. Fingers unarmed, 0.7–[1.1] × palm length.

P2–4 (P3 lost in holotype): Setose and spinose. Meri successively shorter posteriorly: P3 merus 0.8–0.9 × length of P2 merus, P4 merus 0.7–0.9 × length of P3 merus. P2 merus, [0.5]–0.6 × carapace length, [3.5]–4.5 × as long as broad, [1.1]–1.3 × as long as P2 propodus; P3 merus 3.5–4.0 × as long as broad, 0.9 × as long as P3 propodus; P4 merus 3.0–[3.3] × as long as broad, 0.9–[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. Carpi with 4 spines on extensor margin on P2–3, unarmed on P4; distal spine prominent on P2–3, absent on P4; granules below extensor margin on lateral surface of P2–4; flexor margin unarmed. Propodi stout, [4.3–4.7]5.0–5.8 × as long as broad; extensor margin irregular, armed with 3 spines; flexor margin with 3–4 slender movable spines in addition to distal pair. Dactyli [0.7–0.8]0.6–0.8 × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 5–6 movable spines.

Eggs: Ov. F carried approximately 15– 40 eggs of 0.4–0.5 mm diameter.

Live colour. Unknown.

Genetic data. COI and 16S, Table 1.

Distribution. Indonesia, Marsegu Island (Seram Island), Papua New Guinea, and Western Australia, from 0 to 27 m.

Remarks. Phylladiorhynchus talaus belongs to the group of species having 2 epigastric spines, 1 hepatic spine and 3 spines on anterior branchial margin. The closest species is P. triginta Schnabel & Ahyong, 2019 from Tasman Sea and Norfolk Island, but they are easily differentiated by several characters (see the differences under the Remarks of this species).

The two sequences of P. talaus from Western Australia and Papua New Guinea diverged by 2.3% (COI) and 0.2% (16S), respectively. The specimens of P. talaus range from 1.8 to 2.7 mm postorbital carapace length.

Figures

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.

FIGURE 51. Phylladiorhynchus talaus n. sp., holotype ovigerous female 1.9 mm (WAM C51399); E, paratype female 2.2 mm (MNHN-IU-2014-13664): 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, right P2, lateral view. G, right P4, lateral view. H, dactylus of right P2, lateral view. Scale bar: A, E–G = 1.0 mm; B–D, H = 0.6 mm.