Phylladiorhynchus porteri, 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 : 118-120

Phylladiorhynchus porteri n. sp.

( Figs. 45 , 50D )

Type material. Holotype. Chile, Valparaiso, coll. Porter, 1899: M 2.7 mm (MNHN-IU-2019-2598 (Ga-763)).

Paratypes. Chile, Valparaiso, coll. Porter, 1899: 3 M 2.0– 2.7 mm, 4 ov. F 2.4–2.8 mm (MNHN-IU-2014-23831 (Ga-763)) .

Etymology. Named after C.E. Porter, Chilean naturalist, who collected the specimens.

Description. Carapace: As long as broad; transverse ridges with dense short setae, and few scattered long thick setae. Gastric region slightly convex with 4 transverse ridges: epigastric ridge distinct with 2 or 3 (if specimen is massive) pairs of spines in transverse row, innermost pair always the largest, outer pair(s) prominent, smaller or absent, sometimes indicated by granules; anterior protogastric ridge medially uninterrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge medially interrupted, with several median scales, laterally interrupted by cervical groove, laterally continuing uninterrupted to first branchial spine; anterior metagastric ridge scale-like. Mid-transverse ridge uninterrupted, preceded by distinct cervical groove, followed by 2 uninterrupted or minutely interrupted ridges, interspersed with 1 short lateral ridge. Lateral margins convex, with 7 spines: first anterolateral spine well-developed, reaching anteriorly to level of lateral orbital spine, second spine (hepatic) small to obsolescent, slightly dorsomesially from lateral margin, and followed by 5 branchial spines behind distinct anterior cervical groove (3 anterior and 2 posterior). Rostrum leaf-like, lanceolate, horizontal, dorsally flattish or slightly concave, 1.4–[1.8] × as long as broad, length 0.4 and breadth [0.2]–0.3 that of carapace; lateral margins smooth and convex, with well-developed supraocular basal spines and small subapical spines. Pterygostomian flap ending in blunt tooth; upper margin unarmed.

Thoracic sternum: As wide as long. Sternite 3 moderately broad, 1.8–[2.0] × as wide as long, anterior margin convex. Sternite 4 narrowly contiguous to sternite 3; surface depressed in midline, smooth; greatest width [2.9]–3.0 × that of sternite 3, 2.0– [3.0] × 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 only; tergites 5–6 smooth.

Eye: Eyestalk length about [0.9]–1.0 × broader than long, peduncle distally setose, not distinctly expanded proximally, with few short transverse striae on lateral surfaces; maximum corneal diameter 0.7–[0.8] × rostrum width, as wide as eyestalk (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 distal spines laterally and mesially. Article 3 with distomesial and distolateral spines. Article 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 one much larger spine on flexor margin.

P1 (only in males, all missing in females): [3.0] × carapace length, subcylindrical, spiny and with dense long stiff setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus 1.4 length of carapace, [1.6]–2.3 × as long as carpus. Carpus 1.5–[1.7] × as long as wide. Palm [1.2]–1.4 × carpus length, 1.8– [1.9] × as long as broad. Fingers 0.8 × palm length; movable and fixed fingers with several proximal marginal spines.

P2–4: (attached legs only) Stout, densely setose and spinose. Meri successively shorter posteriorly: P3 merus 0.6 × length of P2 merus, P4 merus 0.8 × length of P3 merus. P2 merus, 0.8 × carapace length, 2.7– [3.6] × as long as broad, 1.3– [1.6] × as long as P2 propodus; P3 merus 4 twice as long as broad, 1.3 × as long as P3 propodus; P4 merus 3.6 × as long as broad, 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, unarmed; flexor margins irregular, with distal spine on P2–3, distal spine absent in P4. Carpi with prominent spines on extensor margin on P2–3, unarmed on 4; 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 stout, [3.5]3.3–4.3 × as long as broad; extensor margin irregular usually armed with 1–4 well-developed spines; flexor margin with 4 slender movable spines in addition to distal pair. Dactyli 0.6–[0.8] × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 4–6 movable spines.

Eggs. No data.

Live colour. Unknown.

Genetic data. No data.

Distribution. Chile, Valparaíso, unknown depth.

Remarks. Phylladiorhynchus porteri belongs to the group of species having usually 4 spines on the epigastric ridge, the anterior metagastric ridge scale-like, a very small hepatic spine, the anterior margin of the thoracic sternite 3 convex and one spine on the flexor margin of the Mxp3 merus. Phylladiorhynchus porteri is closely related to P. lenzi ( Rathbun, 1907) , from Chile. However, they can be easily distinguished by the following aspects:

- The rostrum is more lanceolate in P. porteri than in P. lenzi .

- The anterior mesogastric ridge is medially interrupted, with few medial scales in P. porteri , whereas this ridge is uninterrupted in P. lenzi .

- The distomesial and the proximal lateral spines of the antennular article 1 are small or minute in P. lenzi , whereas these spines are well developed in P. porteri .

- The spines on the P2–4 meri are stronger in P. porteri than in P. lenzi . Furthermore, the extensor margin of the propodus has well developed spines in P. porteri , being unarmed in P. lenzi .

The specimens of Phylladiorhynchus porteri range from 2.0 to 2.8 mm postorbital carapace length.

Figures

FIGURE 45. Phylladiorhynchus porteri n. sp.,A–D, F–H, holotype male 2.7 mm (MNHN IU-2019-2598 (Ga-763)), G, paratype male 2.0 mm (MNHN- IU-2014-23831): 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, left P1, dorsal view. F, right P2, lateral view. G, attached leg, presumably left P3, lateral view. H, 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.