Munidopsis messingi, Rodríguez-Flores & Bracken-Grissom & Lemaitre & Felder & Nizinski, 2025

Rodríguez-Flores, Paula C., Bracken-Grissom, Heather D., Lemaitre, Rafael, Felder, Darryl L. & Nizinski, Martha S., 2025, A new squat lobster (Crustacea, Decapoda, Munidopsidae) from the western Atlantic with redescription of Munidopsis expansa Benedict, 1902 and several range extensions, ZooKeys 1248, pp. 321-340 : 321-340

Munidopsis messingi sp. nov.

Figs 1 , 2 A – J , 3 A – C , 4 A – D

Material examined.

Holotype. • North Atlantic Ocean, Curaçao, DROP, 2016, CURI 16056 , Curaçao Sea Aquarium, east of downline, Bapor Kibra , 12.082254 - 68.897365, 253–264 m, 14 October 2016: M 11.5 mm ( USNM 1424972 , GenBank Accession No. PV 297963 ) . Paratypes. • North Atlantic Ocean, Atlantic coast of Florida , 27.07707, - 79.319214, no depth or date data: 1 ov. F 23.5 mm ( MCZ: IZ 172998 , ex-HBG 9802), GenBank Accession No. PV 297964 ). • Curaçao, DROP, 2012, CURI 12032 , off of Substation Curaçao downline , 12.040327, - 68.781043, no depth data, 29 May 2012: 1 F 19 mm ( USNM 1198913 ) . • CURI 11529 , Headed East out of gate / substation , no locality data, 173–259 m, 27 May 2011: 1 F 18.5 mm ( USNM 1160002 ) . • CURI 14047 , East at Substation Curaçao downline , 215–309 m, 12.083197, - 68.899058, 23 September 2014: 1 M 13.0 mm ( ULLZ 15927 , USNM 1406053 ) . • CURI 14055 , off of Substation Curaçao downline , 12.083197, - 68.899031, 142–280 m, 24 September 2014: 1 M 9.2 mm ( ULLZ 15933 , USNM 1406056 ) . • CURI 17020 , Curaçao Sea Aquarium east of downline, Bapor Kibra , 271 m, 12.0823, - 68.8973, 2 November 2017: 1 M 10.9 mm ( USNM 1554267 , GenBank Accession No. PV 810825 ) .

Etymology.

Named after Charles “Chuck” Messing, recently deceased, in honor of his dedication to and passion for ocean exploration, and his “larger than life” entertaining and kind personality. This is in recognition of his significant contributions to the biology, natural history and taxonomy of echinoderms, crustaceans and other invertebrates.

Diagnosis.

Carapace dorsally covered with short setae, pilose, gastric, hepatic and anterior branchial areas smooth, posterior branchial area with short scales or scattered granules (Fig. 3 A – C ). Rostrum moderately broad, dorsally elevated and with median carina, distally trifid. Frontal margin slightly concave behind ocular peduncle. Orbit excavated, orbital angle above antennal peduncle produced into sharp spine. 1–3 small spines close to anterolateral angle. Anterolateral spine strong. Branchial margin armed with 2 strong spines. Abdominal tergites unarmed. Telson divided into 10 plates. Sternite 3 anterolaterally rounded, anterior margin with median lobe flanked by 2 lobes, sternite 4 broadly subtriangular. Eyes unarmed, movable, epistomial spine present, cornea globular, elongated. Article 1 of antennule with dorsolateral and distolateral spines. Article 1 of antenna with strong distomesial spine and distolateral spines. Mxp 3 merus with 3 strong spines on flexor margin, small distal spine, extensor margin with 4 spines. P 1 stout, length less than twice PCL; meri and carpi armed with distal spines; palm and fingers unarmed; fixed finger without denticulate carina on distolateral margin; dactylus dorsally carinate. P 2–4 stout; meri carinate on dorsal margin; dactyli slender, distally curving, flexor margin with 6–8 small teeth decreasing proximally along entire length. Epipods present on P 1 and 2.

Description.

Carapace: Slightly broader than long, widest at midlength; moderately convex from side to side. Dorsal surface pilose; gastric, hepatic and anterior branchial areas smooth, densely covered with short setae; posterior branchial area with short scales or scattered granules (Figs 2 A , 3 A, C ); cardiac and intestinal regions covered with larger scales, each scale with few short setae. Regions well delineated by deep furrows including distinct anterior and posterior cervical grooves. Gastric region slightly elevated. Cardiac region divided by a transverse furrow in anterior and posterior cardiac regions. Posterior margin unarmed, preceded by elevated ridge. Rostrum moderately broad, dorsally elevated, width 0.2–0.3 × anterior width of carapace, directed strongly upwards, dorsally carinate, distally trifid, with strong median spine twice as long as lateral spines (Fig. 2 A ), 0.4 × PCL, 1.3–1.8 × as long as broad. Frontal margin concave behind ocular peduncle, orbital angle above antennal peduncle produced into sharp spine, reaching or surpassing distal margin of cornea; spine below antennal proximal mesial angle, ventral to frontal margin, close to epistomial region; 1–3 small spines close to anterolateral spine. Lateral margins slightly convex, converging posteriorly; anterolateral spine sharp; anterior branchial margin with 1 strong spine; 1 strong branchial spine just behind posterior branch of cervical groove. Pterygostomian flap surface covered with granules and scales, anteriorly narrowly rounded.

Sternum: 0.9 × as long as broad, maximum width at sternite 7. Sternite 3 broad, 3.0 × wider than long, anterolaterally rounded, anterior margin with median lobe flanked by 2 subacute lobes. Sternite 4 narrowly elongated anteriorly; surface depressed in midline, with scattered short scales; greatest width 2.3 × that of sternite 3, 1.7 × wider than long.

Pleon: Unarmed; tergite 2 with 2 elevated transverse ridges, lateral parts of dorsal surfaces covered with granules and scales; tergites 3–6 with only anterior; tergite 6 with weakly produced posterolateral lobes and nearly transverse posteromedian margin. Telson composed of 10 plates, 1.5 × as wide as long.

Eye: Eyestalk movable, partially concealed by rostrum; peduncle with few granules, shorter than cornea length; cornea, elongated, longer than peduncle, ovoid; lateral surface contiguous to epistomial spine, epistomial spine ventral to frontal margin.

Antennule: Article 1 of peduncle with granules on anterolateral ventral surface, armed with subequal dorsolateral and distolateral spines; distomesial margin with strong spine.

Antenna: Peduncle slightly exceeding eye. Article 1 with strong distomesial and distolateral spines, each surpassing distal margin of article 2. Article 2 with distomesial and distolateral spines, distolateral spine much stronger. Article 3 armed with small distomesial and distolateral spines. Article 4 unarmed.

Mxp 3: Lateral surface with few granules. Ischium as long as merus measured on extensor margin merus with 3 strong spines subequal in size and 1 smaller distal spine on flexor margin; extensor margin with 4 spines, distal spine strongest.

P 1: Stout, with numerous minute granules and short scales, each scale marginally with few short setae, 1.3 × longer than PCL. Merus 2.2 × carpus length, distally with stout spines. Carpus 0.9 × longer than broad, with some short distal spines, few acute granules on dorsal surface. Palm unarmed, stout, slightly longer than carpus, 1.2 × longer than broad. Fingers unarmed, 1.2 × longer than palm, opposing margins nearly straight, not gaping, spooned; fixed finger without denticulate carina on distolateral margin, mobile finger with dorsal carina.

P 2–4: Stout, pilose, with short scales and granules, cylindrical in cross-section, slightly decreasing in size posteriorly. P 2 merus stout, overreaching tip of P 1, 0.6 × carapace length, 2.7 × longer than high, equal to 1.1 × length of P 2 propodus. P 2–4 meri decreasing in length posteriorly (P 3 merus 0.9 × length of P 2 merus, P 4 merus 0.85 × length of P 3 merus); extensor margin carinate, with small granules along entire length, distal part flattish ending in thick spine; flexor margin granulate; P 2–4 carpi each with 1 thick distal spine on extensor margin, lateral surface with granulated carina; P 2–4 propodi 4.0–5.0 × as long as high, triangular in cross-section, unarmed. P 2–4 dactyli 0.5 × length of propodi; distal claw short, moderately curved; flexor margin distally curved, with 6–8 dactylar teeth on entire length, each tooth with slender corneous spine, ultimate tooth closer to penultimate tooth than to dactylar angle.

Epipods: Present on P 1 and 2.

Coloration: Carapace, P 1 –4 and chelipeds entirely light to reddish orange. Distal parts of rostrum, articles and spines whitish (Fig. 4 A – D ).

Ecology.

Unknown.

Distribution.

Curaçao and East coast of Florida; 173–264 m.

Remarks.

This species belongs to a group of species having a trifid and elevated rostrum, an unarmed carapace and abdomen, 8–10 telson plates, a stout P 1 that is less than twice the PCL, stout P 2–4, and epipods on P 1 and 2. In addition to M. messingi sp. nov., this species group includes M. expansa Benedict, 1902 from the western Atlantic and M. testuda Rodríguez-Flores, Seid, Rouse & Giribet, 2023 , known only from the Galapagos Islands in the eastern Pacific. The new species can be distinguished from the aforementioned two species by the following morphological characters:

The carapace gastric, hepatic and branchial regions are covered with granules and scales in M. expansa and M. testuda , but these areas are covered with dense pilosity in the new species.

The carapace anterolateral angle is produced as a broad spine in M. testuda and M. expansa , whereas the spine is sharp, much longer and preceded by a cluster of 1–3 spines in the new species.

The carapace excavate orbit in the new species terminates laterally in a sharp, long spine, sometimes surpassing the distal margin of the cornea, but this spine is absent in M. expansa and M. testuda .

The lateral margin of the rostrum is concave in M. testuda , slightly convex in the new species and divergent in M. expansa .

The distomesial angle of the antennular peduncle article 1 is armed with a distinct spine in the new species, whereas it is unarmed in M. expansa and M. testuda .

The new species differs from M. expansa and M. testuda in having a much longer distolateral spine of the antennal peduncle article 1.

The flexor margin of Mxp 3 merus is unarmed in M. expansa , whereas it is armed with 3 distinct spines in the new species.

The flexor margin of P 2–4 dactyl is armed with 6–8 teeth in the new species but has 11–12 teeth M. expansa and M. testuda .

Genetic divergence for the COI marker ranged from 14.0 to 15.6 % between the new species and its closely related congeners (see Table 1 for genetic distances).

Figures

Figure 1. Map depicting locations for species of Munidopsis treated in present study of the Gulf of Mexico, Caribbean, and adjacent Atlantic waters off Florida.

Figure 2. Munidopsis messingi sp. nov., M 11.5 mm PCL, holotype (USNM 1424972, CURI 16056), Curaçao. A. Carapace and abdomen, dorsal view; B. Sternal plastron; C. Telson; D. Cephalic region, showing antennular and antennal peduncles, ventral view; E. Left Mxp 3, lateral view; F. Right P 1, dorsal view; G. Right P 2, lateral view; H. Right P 3, lateral view; I. Right P 4, lateral view; J. Right P 4 dactyli, lateral view. Scale bars: 2 mm.

Figure 3. Munidopsis messingi sp. nov., 3 D rendering of micro-CT images, 23.5 mm PCL, paratype (: IZ 172998, HBG 9802) east coast of Florida: A. dorsal B. ventral; C. lateral views.

Figure 4. Munidopsis messingi sp. nov., color images of fresh specimens, 1 M 10.9 mm PCL, paratype (USNM 1554267 [CURI 17020]), Curaçao: A, B. M 13.0 mm PCL, paratype (USNM 1406053 [ULLZ 15927; CURI 14047]), Curaçao, C. M 9.2 mm PCL paratype (USNM 1406056 [ULLZ 15933; CURI 14055]), Curaçao, D. A. Dorsal habitus, abdomen flexed; B. Dorsal habitus, abdomen extended; C. Dorsal habitus, damaged abdomen extended; D. Dorsal habitus, abdomen extended. Photographs by DLF.