Munidopsis verrilli Benedict, 1902

Munidopsis verrilli Benedict, 1902 View in CoL

Figs 7 View Figure 7 , 8 View Figure 8

Munidopsis verrilli Benedict 1902: 291, fig. 3 (type locality: off southern California). — Rathbun 1904: 167. — Schmitt 1921: 169, fig. 108. — McCauley 1972: 415 (list). — Luke 1977: 26. — Wicksten 1982: 245 (list). — Wicksten 1989: 316 (list). — Baba and Poore 2002: 245, fig. 10. — Poore 2004: 238, fig. 65 k. — Baba 2005: 194, 298. — Osawa and Takeda 2007: 142, fig. 6 C, D. — Baba et al. 2009: 275, figs 252, 253. — Komai and Matsuzaki 2016: 103, figs 7, 8. View in CoL

Munidopsis sp. cf. M. verrilli — Rodríguez-Flores 2025: 21.

Material examined.

USA – off California • 9 males ( 5–17 mm), 6 females ( 8–13 mm), 4 ovigerous females ( 13–17 mm); Catalina Basin, MET Sta. 109 ; 33°11'N, 118°30'W; 1198–1234 m depth; K. Smith and S. Luke leg.; 31 Jan. 1981; collected by 40’ otter trawl of R/V New Horizon; SIO-BIC C 4907 GoogleMaps .

Description.

Carapace: distinctly longer than broad (excluding rostrum). Frontal margins oblique, antennal spine well developed. Lateral margins divergent posteriorly, broadest at median posterior branchial margin, bearing sparse long setae; anterolateral spine short, anterolaterally directed; anterior branchial margin with 3 spines; posterior branchial margin convex, with spine at end of posterior cervical groove. Posterior margin concave, submarginal ridge elevated. Dorsal surface with regions well defined, covered with transverse, interrupted short rugae; rugae longer and more strongly elevated on posterior branchial region, sparsely bearing short setae on gastric and lateral branchial region; cervical groove deep. Gastric region strongly elevated, with pair of epigastric spines. Cardiac region clearly delineated, lateral and posterior cardiac regions elevated, median transverse groove deep. Intestinal region subtriangular. Rostrum spiniform or narrowly triangular, nearly horizontal, ~ 0.2 remaining carapace length, 2.5 × longer than broad; dorsal surface smoothly carinate, unarmed or rarely with small median spine. Pterygostomial flaps with oblique rugae on surface, anterior end with small spine.

Sternum: slightly longer than broad, widening posteriorly. Sternite 3 1.8 × broader than long, divided into 2 parts by longitudinal median groove; anterior margin with median notch, bearing small lateral tooth. Sternite 4 slightly broader than long, anterior part with longitudinal median groove, narrowly elongated; posterior part broad, surface depressed and with short scale-like rugae. Sternites 5–7 separated by transverse ridges, with interrupted median groove.

Pleon: tergites smooth and unarmed. Tergite 2–4 each with 2 transverse ridges bearing fine setae anteriorly, posterior ridge on tergite 4 low and interrupted. Tergite 5 smooth, without distinct groove and ridge. Tergite 6 with straight or slightly concave posteromedian margin. Telson composed of 9 or 10 plates.

Eye: eyestalk immovable. Peduncle short, broader than cornea. Mesial eyespine relatively long, anteriorly directed, reaching to proximal 0.3–0.4 of rostrum. Lateral eyespine short. Cornea globular.

Antennule: article 1 longer than broad; distal margin with strong ventrolateral and dorsolateral spines subequal in size and short mesial spine; lateral surface slightly inflated, with oblique groove extending from base of dorsolateral distal spine to median part of ventral surface; mesial margin straight.

Antenna: peduncle thick, reaching to level of midlength of rostrum. Article 1 with distomesial and distolateral spines both reaching midlength of article 2. Article 2 with short distolateral spine reaching midlength of article 3. Article 3 subrectangular, distomesial and distolateral margins minutely denticulate. Article 4 short.

Mxp 3: ischium slightly shorter than merus, disto-extensor corner with small but acute spine; crista dentata well-developed. Merus with extensor margin slightly convex, rugose, armed with small distal spine; flexor margin denticulate, bearing 3 small spines; lateral surface with short rugae. Carpus with extensor margin slightly rugose. Propodus subrectangular, narrowed distally, extensor and flexor margins subparallel.

P 1: subequal, 1.5 × as long as pcl, densely covered with long setae on surfaces and margins. Ischium short, ~ 1 / 2 of merus length; dorsodistal margin armed with acute spine; ventrodistal margin produced, with strong subterminal spine; surfaces covered with short rugae. Merus ~ 1 / 2 of pcl; surfaces bearing short transverse rugae; distal margin with strong dorsal, dorsomesial, ventromesial and ventrolateral spines: dorsal spine followed by row of spines along midline of dorsal surface, dorsomesial spine followed by strong median spine on mesial surface, ventromesial spine followed by 2 strong spines on ventral surface. Carpus half of merus length; surfaces with short rugae; distal margin with strong dorsal, dorsolateral and dorsomesial spines; dorsomesial spine followed by row of 2 spines along dorsomesial margin. Chela compressed dorsoventrally, palm 0.6 merus length, 1.6 × longer than broad, with short rugae on surfaces; lateral margin straight; mesial margin armed with 2 spines. Fingers approximately as long as palm, thickly setose distally; occlusal margins serrated and distally spooned, with low proximal triangular process on fixed finger.

P 2–4: slender, with long setae densely on margins and surfaces; lateral surface with short scale-like rugae. P 2 ~ 1.8 × pcl, nearly reaching tip of P 1 dactylus. Meri slender, decreasing in length posteriorly, P 2 merus 0.6 pcl, P 3 and P 4 merus ~ 0.8 and 0.7 P 2 merus length, respectively; P 2 merus ~ 7.1 × longer than broad (length / width ratio on P 3 and P 4 meri, 5 and 4.5, respectively); extensor margin armed with row of spines decreasing in size proximally; flexor margin rugose, with strong distal spine. Carpi somewhat decreasing in length posteriorly, subequal in width, P 2 carpus ~ 0.4 length of P 2 merus, P 3 and P 4 carpi 0.9 and 0.8 length of P 2 carpus, respectively; extensor margin with 2 longitudinal ridges, mesial ridge usually with 4 spines, lateral ridge with relatively small distal spine; flexor margin with minute distal spine. Propodi slender, subequal in width on P 2–4; P 2 propodus 0.9 length of P 2 merus, 9.0 × longer than broad, P 3 and P 4 propodi 0.9 length of P 2 propodus; extensor margin slightly rugose, unarmed; flexor margin with pair of distal corneous spines preceded by corneous spine located on distal 0.2. Dactyli 0.4 or 0.5 length of propodus; extensor margin slightly rugose, proximally straight, distal claw curving; flexor margin straight, with 10–12 movable corneous spines on distal 0.8 length, each spine present on low triangular tooth, ultimate spine closer to penultimate spine than to distal claw.

P 1 –4 without epipods.

Habitat.

Clay ( Baba 2005) and manganese-crust bottom ( Rodríguez-Flores 2025).

Distribution.

West Pacific: south to Australia and Indonesia and north to Japan; Central Pacific: Johnston Atoll; Eastern Pacific: from off Oregon to southern California; depth 732–4169 m.

Remarks.

Baba (2005) noted that the holotype of M. verrilli has a denticulate carina on the distolateral margin of the P 1 fixed finger, while such feature is absent in our specimens. Baba (2005) regarded this character as an intraspecific variation within this species, because it was also missing in other specimens he examined from the type locality.

Baba and Poore (2002) reported a female from Tasmania, Australia. The diagnosis and figures of their specimens showed three rows of spines on the P 1 merus including a median spine on the mesial surface, and three spines along the flexor margin of the P 2 and P 3 propodi. These characters match the specimens examined of M. verrilli from California waters. A single male from the Makassar Strait exhibits the similar traits ( Baba 2005). Meanwhile, the key interspecific characters, such as the elevated lateral cardiac region of the carapace, short mesial eyespine, median spine on the mesial surface of P 1 merus and a row of strong spines on the extensor margin of P 2–3 carpi, can be observed from the photos of specimens from the Okinawa Trough, northeast of Taiwan Island and Nemuro Strait ( Osawa and Takeda 2007; Baba et al. 2009; Komai and Matsuzaki 2016), indicating that these West-Pacific specimens also belong to M. verrilli .

Munidopsis verrilli appears independent of chemosynthetic environments. The California specimens have been taken from mud bottom by otter trawl or beam trawl ( Luke 1977). In the Makassar Strait, it was collected from clay bottom ( Baba 2005) and in Johnston Atoll, it was obtained on manganese-crust bottom ( Rodríguez-Flores 2025). Osawa and Takeda (2007) obtained the specimen by beam trawl in the Okinawa Trough, while Komai and Matsuzaki (2016) captured the specimens with commercial gill net. Given the wide distribution range, molecular methods are needed to confirm the taxonomic consistency and genetic connectivity among populations in different localities.

Rodríguez-Flores et al. (2023) reported M. similis from deep waters off southern California, which is identical to the type locality of M. verrilli . Their COI data show only 0.8–3.8 % genetic distances from M. cf. verrilli ( USNM 1464026 and 1188648), suggesting a very low divergence ( Rodríguez-Flores et al. 2023). Munidopsis similis ranges from the West Atlantic to the West Pacific and exhibits low genetic divergence among populations ( Rodríguez-Flores et al. 2023). In this case, the taxonomic validity of M. verrilli may be questionable. Further molecular evidence of M. similis , particularly from the topotypic material collected off New England, is essential to resolve the systematic relationship between the two species.