Phylladiorhynchus lenzi ( Rathbun, 1907 )

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 : 77-79

Phylladiorhynchus lenzi ( Rathbun, 1907)

( Fig. 28 )

Galathea lenzi Rathbun, 1907: 49 , pl. 3, fig. 1 (Corral, Chile).— Porter, 1916a: 96 (Corral, Chile).— Porter, 1916b: 112 (Corral, Chile).

Records requiring verification:

Galathea latirostris . — Lenz, 1902: 742 (Juan Fernandez Island) (not Galathea latirostris Dana, 1852 )

Galathea lenzi . — Balss, 1922: 334 (Juan Fernandez island).— Haig, 1955: 31, fig. 6 (Juan Fernandez island).— Retamal, 1981: 22 (Corral to Concepcion, Chile).— Andrade, 1985: 111 (Juan Fernandez island). — Castilla & Rozbaczylo, 1987: 183 (list, Juan Fernandez).— Poupin, 2003: 24 (list, Chile, Salas y Gomez islands).— Retamal, 2004: 60, fig. 10 (Chilean coast, Salas y Gomez, Juan Fernandez islands).

Phylladiorhynchus pusillus . —De los Ríos Escalante & Ibáñez Arancibia, 2016: 79 (Easter Island, list).— Mujica et al., 2019: 775, figs. 1–5 (larval development, Easter Island).

Type material. Lectotype. Chile, Corral , Valdivia: ov. F 2.7 mm ( USNM 32261 ).

Paralectotype. Chile, Corral , Valdivia: 1 ov. F 2.6 mm ( USNM 32261 ) .

Description. Carapace: Slightly wider than long. Gastric region slightly convex with 4 transverse ridges: epigastric ridge distinct with 2 median pairs of spines symmetrically distant of median area; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge not medially interrupted, laterally interrupted by cervical groove, laterally continuing uninterrupted to first branchial spine; anterior metagastric ridge scale-like. Mid-transverse ridge uninterrupted, preceded by shallow or undistinct 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, slightly dorsomesially from lateral margin, and followed by 5 branchial spines behind distinct anterior cervical groove (3 anterior and 2 posterior). Rostrum leaf-like, horizontal, dorsally flattish or slightly concave, 1.3 × as long as broad, length 0.3 and breadth 0.2 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 smooth.

Thoracic sternum: As wide as long. Sternite 3 moderately broad, twice as wide as long, anterior margin convex, anterolaterally convex. Sternite 4 widely contiguous to sternite 3; surface depressed in midline, smooth; greatest width 3 × that of sternite 3, 3.2 × as wide as long.

Pleon: 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 1.2 × broader than long, peduncle distally setose, not distinctly expanded proximally; maximum corneal diameter 1.2 × rostrum width, as wide as eyestalk (as wide as maximum peduncle width).

Antennule: Article 1 slightly longer than wide, with 4 well-developed distal spines: distomesial spine welldeveloped; proximal lateral spine absent or present as a granule.

Antenna: Article 1 with prominent mesial process distally falling well short of lateral antennular spine. Article 2 and 3 with well-developed distomesial and distolateral spines. 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 margin and 1 much larger spine at flexor margin.

P1: 3 × carapace length; subcylindrical, spiny; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus 1.1 length of carapace, 1.8 × as long as carpus. Carpus 1.8 × as long as wide. Palm 1.2 × carpus length, 1.8 × as long as broad. Fingers 0.8 × palm length; some marginal spines along proximal half of movable and fixed fingers.

P2 (presumably, other walking legs lost): Stout, moderately setose and spinose. Merus, 0.7 × carapace length, 3.7 × as long as broad, 1.5 × as long as propodus; extensor margin with row of spines, proximally diminishing, with prominent distal spine; flexor margin irregular, with distal spine; lateral surface with scales. Carpus with 3 spines on extensor margin; row of small acute granules below extensor margin on lateral surface; flexor margin unarmed other than distal spine. Propodi stout, 3.8 × as long as broad; extensor margin irregular unarmed; flexor margin with 3 slender movable spines in addition to distal pair. Dactyli 0.6 × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 4 movable spines.

Live colour. Unknown.

Genetic data. No data.

Distribution. Only known from Corral, Valdivia ( Chile), unknown depth.

Remarks. Phylladiorhynchus lenzi was described by Rathbun (1907) from 4 specimens collected by C.E. Porter in waters of Corral, Valdivia Province ( Chile), with a very short diagnosis and one photo. The species was later reported in other localities along the coast (e.g. Concepcion area), as well as in the oceanic islands (e.g. Juan Fernandez, Salas y Gomez) (see above). However, until now, no complete description of the species existed, avoiding a comparison among the specimens from different localities as well as with other species.

Furthermore, when examining specimens from different Chilean localities, e.g. Corral (type specimens) and Valparaiso (coll. Porter, 1899, deposited in the MNHN of Paris) we found that they belong to two different species ( P. lenzi and P. porteri ). Unfortunately, we failed to examine specimens from Chilean oceanic islands, so the identity of the specimens of Phylladiorhynchus reported from these islands remains to be confirmed. Phylladiorhynchus lenzi has been considered a synonym of P. pusillus ( Henderson, 1885) ( Baba et al. 2008; Schnabel & Ahyong 2019).

Phylladiorhynchus lenzi 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. This group contains four species: P. pusillus from New Zealand and Australia, P. lenzi , from Chile, P. porteri , from Chile, and P. poeas from French Polynesia. Differences between P lenzi and P. porteri are given under the Remarks of the latter species. Phylladiorhynchus lenzi can be distinguished from P. pusillus and P. poeas by subtle but constant differences:

- The proximal lateral spine of the antennular article is always distinct in P. pusillus , whereas this spine is very small to indistinct in P. lenzi and P. poeas .

- The antennal article 3 is armed with a small distomesial spine in P. pusillus , whereas this article has welldeveloped distomesial and distolateral spines in P. lenzi and P. poeas .

Figures

FIGURE 28. Phylladiorhynchus lenzi (Rathbun, 1907), lectotype ovigerous female 2.7 mm (USNM 32261): 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, right P1, dorsal view. F, left P2, lateral view. Scale bar: A, E-F = 1.0 mm; B–D = 0.6 mm.