Cheramoides samba Hernaez and Souza-Filho 2025, sp. n.
Creators: name: Hernáez, Patricio
name: Souza-Filho, Jesser F.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Callianassidae
Cheramoides
Cheramoides samba

description: Cheramoides samba Hernáez and Souza-Filho sp. n.
(Figures 1–3)
Callianassa marginata – Coelho and Ramos 1972: 161 [not C. marginata Rathbun, 1901]; Coelho et al. 1980: 63 [not C. marginata Rathbun, 1901]
Callichirus marginatus – Coelho and Ramos-Porto 1980: 136 [not C. marginatus (Rathbun, 1901)]
Cheramus marginatus – Coelho 1997: 144 [not C. marginatus (Rathbun, 1901)]; Melo 1999: 360, fig. 240 [not C. marginatus (Rathbun, 1901)]; Coelho et al. 2007: 5 [not C. marginatus (Rathbun, 1901)]
Type material
BRAZIL: Maranhão: holotype: male, cl: 3.2 mm, left second pereiopod missing, right cheliped detached, third to fifth pereiopods missing, station GM 08, 2.067°S, 42.717°W, 67 m, mud bottom, R/V Almirante Saldanha coll., 2 June 1969, MOUFPE 8413 (as Cheramus marginatus, Coelho 1997). Paratypes: 5 males, cl: 2.7–3.1 mm, same data as holotype, MOUFPE 21627 (as Cheramus marginatus, Coelho 1997); 6 females (3 ovigerous), cl: 2.0– 3.6 mm, same data as holotype, MOUFPE 21626 (as Cheramus marginatus, Coelho 1997).
Non-type material
BRAZIL: Amapá: female, major cheliped and abdomen missing, cl: 5.0 mm, station GM 211, 4.458°S, 50.0.25°W, 183–224 m, mud bottom, R/V Almirante Saldanha coll., 16 September 1969, MOUFPE 1878 (as Cheramus marginatus, Coelho 1997); 2 males, both damaged, cl: 3.0– 3.7 mm, station GM 206, 5.150°S, 50.700°W, 172 m, mud bottom, R/V Almirante Saldanha coll., 1971, MOUFPE 8410 (as Cheramus marginatus, Coelho 1997). Maranhão: female, damaged, cl: 3.5 mm, station AS 1739, 2.083°S, 42.733°W, 46 m, mud bottom, R/V Almirante Saldanha coll., 31 October 1967, MOUFPE 8415 (as Cheramus marginatus, Coelho 1997); male, damaged, cl: 2.4 mm, station AS 1738A, 1.925°S, 42.75°W, 75 m, mud bottom, R/ V Almirante Saldanha coll., 31 October 1967, MOUFPE 8415 (as Cheramus marginatus, Coelho 1997); female, cl: 4.3 mm, station AS 1739, 2.083°S, 42.733°W, 46 m, mud bottom, R/V Almirante Saldanha coll., 31 October 1967, MOUFPE 8416 (as Cheramus marginatus, Coelho 1997). Ceará: 2 males, cl: 4.5–4.6 mm, PAVASAS I, station DG 05, 2.258°S, 40.488°W, 45 m, mud bottom, R/V Almirante Saldanha coll., 20 July 1987, MOUFPE 8409 (as Cheramus marginatus, Coelho 1997). Alagoas: female, damaged, all pereiopods missing, cl: 3.8 mm, station AK 80, 10.097°S, 35.788°W, 290 m, mud bottom, R/V Akaroa coll., 4 September 1965, MOUFPE 8417 (as Cheramus marginatus, Coelho 1997). Rio de Janeiro: 3 males, damaged, cl: 2.2–3.6 mm, 2 females, damaged, cl: 3.8–4.0, station AS 2167, 22.970°S, 41.933° W, 53 m, mud bottom, R/V Almirante Saldanha coll., 16 September 1969, MOUFPE 8418 (as Cheramus marginatus, Coelho 1997).
Comparative material examined
Cheramoides marginata (Rathbun, 1901). PUERTO RICO, Mayaguez Harbour: holotype, male, cl: 5.7 mm, 8.200°N, 67.167°W, 295–315 m, United States Fish Commission coll., 20 January 1899, USNM 23778. BARBADOS, Harbour: female, cl: 8.0 mm, NR1-1, 91–366 m, JB Lewis coll., USNM 110209; male, cl: 8.0 mm, NR19-5, 91–366 m, JB Lewis coll., USNM 110213.
Diagnosis
Rostrum acutely triangular, extending beyond eyestalks. Third maxilliped merus with rounded inferior margin, truncate on mesiodistal margin. Superior margin of male major cheliped merus with expansion in midlength. Sixth pleomere with posterior lobes poorly developed. Telson wider than long, posterior margin with median concavity armed with minute acute spine. First pleopod of male uniramous and composed of two articles; third to fifth pleopod endopod with projecting, finger-like appendix interna. Uropods extending beyond posterior margin of telson, uropodal exopod with small spiniform setae on margin of dorsal ridge.
Description
Frontal margin of carapace with acute triangular rostrum flanked laterally by oblique shoulders directed posteriorly (Figure 1 (A)); rostrum inclined downward in lateral view, extending beyond full length of eyestalks in dorsal view (Figure 1 (A,B)). Carapace smooth, with distinct linea thalassinica and well-defined dorsal oval marked posteriorly by transverse cervical groove, cardiac prominence absent; lateral margins of carapace emarginate on posterior part (Figure 1 (A,B)).
Eyestalks (Figure 1 (A)) elongate subtrapezoidal in dorsal view, distal margin with triangular projection, not extending to basal antennular article, dorsal surface concave, cornea subterminal, well-defined, darkly pigmented. Antennular peduncle slightly shorter than antennal peduncle (Figure 1 (A)); second and third articles of antennular peduncle with rows of long setae ventrally, third article about 3 times as long as second article (Figure 1 (A,C)). Antennular flagellum dorsal ramus slightly shorter, heaver and with much denser, longer setae than on ventral flagellum ramus; both flagella with sparse, long tufts of setae, both composed of 10–11 articles (Figure 1 (C)). Antennal peduncle with scaphocerite reduced to a small triangular scale; antennal peduncle fifth article exceeding at least 2/3 to full length of antennular peduncle third article; basal article with excretory pore barely visible, laterally with setose, rounded, weak distal protuberance; second article with scaphocerite oriented laterally, fourth article 1.2 times longer than fifth article, fifth article narrower than others (Figure 1 (A,D)). Antennal flagellum missing in holotype and in all examined specimens.
Mouthparts not dissected. Third maxilliped (Figure 1 (E,F)) without exopod and epipod; endopod large, setose, endopodal ischium-merus broadened, length about 2 times its width; ischium subrectangular, about 1.4 times as long as wide, mesial surface with developed crista dentata consisting of an unique row of sharp, closely denticles on distal 2/3; merus short, subtrapezoidal, broader than long, marginally setose, distal margin truncate, not projecting beyond carpo-meral articulation, with rounded inferior margin; carpus subrectangular, longer than broad; propodus subrectangular, longer than broad, 1.8 times longer than carpus, lower margin with densely setose; dactylus digitiform, less than half as long as propodus, arcuate proximally, upper margin covered with long setae.
Branchial formula as reported for C. marginata by Biffar (1971); branchiae limited to pair of rudimentary arthrobranch on third maxilliped, and a pair of arthrobranchs on each of first through fourth pereopods.
Major cheliped (Figure 1 (G)) heavy and strongly calcified; ischium elongate, superior margin straight, inferior margin with row of well spaced teeth; merus about as long as ischium, superior margin convex and smooth, inferior margin expanded, three small teeth in midlength; carpus subtriangular, slightly shorter than merus, superior and inferior margins smooth; palm rectangular, longer than wide, about 1.5 times as long as carpus; fixed finger straight, flexor margin with two teeth, one in each half, proximal tooth rounded, distal tooth subtriangular; dactylus strong with tip curved downward, slightly longer than fixed finger, shorter than palm, cutting edge with large rectangular tooth proximally and rounded tooth medially, small u-shaped notch near fingertip. Male minor cheliped (Figure 1 (H)) slender; inferior margin of ischium with row of well spaced acute teeth from midlength to articulation with merus, ischium almost equal in length to merus, superior margin straight; merus about 1.8 times longer than wide, superior and inferior margins slightly arcuate, small teeth on the inferior margin of the distal half; carpus as in major cheliped; length of palm about half length of dactylus; fixed finger 1.3 times length of palm, cutting edge unarmed, with tip curved upward, larger than dactylus; cutting edge of dactylus unarmed, superior margin slightly arcuate, with tip curved downward.
Second pereopod (Figure 2 (A)) chelate; ischium unarmed, short, less than half as long as merus, superior margin curved inward; merus more than twice as long as carpus, medial-ventral expansion with long setae, superior margin slightly straight; carpus subtriangular, widening distally, superior margin with long setae; superior and inferior margins of propodus heavily setose, palm slightly shorter than fixed finger; cutting edge of fixed finger unarmed; dactylus lanceolate, densely setose dorsally, cutting edge unarmed.
Third pereopod (on paratype cl 3.0 mm; Figure 2 (B)) pediform; ischium short, unarmed; merus about twice as long as ischium; carpus subtriangular, widening distally, superior margin with depression on central part; propodus rounded, setose marginally; dactylus reduced, digitiform, margins covered with dense setae. Fourth pereopod (on paratype cl 3.0 mm; Figure 2 (C)) simple, unarmed; ischium shorter than merus; merus longest, narrowing distally; carpus less than half as long as merus, widening distally; propodus almost equal in length to carpus; dactylus reduced, digitiform, less than half as long as propodus. Fifth pereopod (on paratype cl 3.0 mm; Figure 2 (D)) subchelate; ischium short, length about 3.1 times less than merus; merus longest, with central expansion on superior margin; carpus subtriangular, widening distally; propodus 1.6 times longer than carpus, inferior margin straight; dactylus curved downward.
Pleon smooth (Figure 3 (A)), glabrous dorsally except for some isolated setae on lateral margins of pleomeres 3 to 5; pleon about 2.3 times as long as carapace; length ratio of first to sixth pleomeres and telson measured along midline 1.2:2.6:1.8:1.6:2.0:2.4:1.0, second to sixth pleomeres translucent in dorsal view. First pleomere strongly calcified, with a median narrowing visible in dorsal view; second pleomere longest, lateral margins parallel; third pleomere narrowing anteriorly in dorsal view; fourth and fifth pleomeres similar in length; sixth pleomere saddle-like, length about 1.1 times its width, longer than telson, posterior lobes poorly developed (Figure 3 (A,B)). Telson short (Figure 3 (B)), about 1.4 times wider than long, convex laterally, and curving towards rounded posterior margin with median concavity armed with blunt spine.
First pleopod of male and female uniramous (Figure 3 (C,D)), composed of 2 articles; male first pleopod with terminal article longer than basal article, terminal article rounded at tip. Second pleopod absent in male but present in female. Third to fifth pleopods biramous (Figure 3 (E)), broad, leaf-like, endopod narrowed, appendix interna digitiform, projected from mesial margin of endopod.
Uropod (Figure 3 (B)) with protopod not divided, smooth dorsally; endopod and exopod heavily setose marginally, both extending beyond posterior margin of telson; endopod elongate oval, about 1.9 times longer than width; exopod longer than endopod, length 1.6 times length of endopod, anterodorsal plate virtually inexistent, just indicated by weak ridge, the latter with small spiniform setae marginally (Figure 3 (G)).
Description of female paratypes
General shape of body and second to fifth chelipeds similar to those of the male. Female major cheliped missing in all female specimens. Female minor cheliped (Figure 1 (I)) slenderer than male minor cheliped; inferior margin of ischium with row of well spaced acute teeth from midlength to articulation with merus; merus elongate, broader than ischium; carpus elongate, subtriangular, almost equal in length to merus; length of palm exceeding half length of dactylus; fixed finger 1.6 times length of palm; dactylus arcuate, longer than fixed finger. First pleopod (Figure 3D) with both articles almost equal in length, terminal article rounded at tip. Second pleopod (Figure 3 (E)) biramous, endopod narrow, longer than exopod, setose distally, appendix interna absent.
Variations
The most noticeable variation is in the handedness of the male major cheliped, which can be located on either the right or the left side. This variation may be due to genetic or regenerative phenomena. Variation in the inclination of rostrum was also noted; the rostrum is usually arched above eyestalks in the holotype and mature specimens but not in juvenile specimens.
Distribution and habitat
South Western Atlantic. Brazil: Amapá, Maranhão, Ceará, Alagoas, Rio de Janeiro (type locality: offshore of the State of Maranhão). The new species is found at depths ranging from 55 to 640 m on muddy bottoms.
Etymology
Derived from the national dance of Brazil, Samba (noun in apposition).
Size
Males cl 2.2–4.6 mm, ovigerous females cl 2.1–2.9 mm, non-ovigerous females cl 2.0–5.0 mm.
Remarks
While some studies previously reported the presence of C. marginata in deeper areas on the continental shelf and slope between Amapá and Rio de Janeiro, Brazil (see Coelho and Ramos 1972; Coelho 1997; Melo 1999), all of these records were undertaken without access to comparative materials from the Puerto Rican type locality. Considering the results of the present study, previous records of Cheramoides marginata (Rathbun, 1901) from Brazilian waters can now be assigned to C. samba sp. n. Cheramoides now consists of four species, namely: C. brachytelson (only known from the Andaman Sea), C. marginata (north-eastern Gulf of Mexico; from Barbados to Puerto Rico; Caribbean Colombia), C. oblonga (only known from Ivory Coast, west Africa) and C. samba sp. n. (from Amapá to Rio de Janeiro, Brazil). Cheramoides samba sp. n. raises to two the number of western Atlantic species in the genus Cheramoides.
The new species is morphologically closest to the Caribbean C. marginata, with which it shares a number of characteristics including the acutely triangular rostrum, the distal article of antennular peduncle about 3 times as long as penultimate article, the third maxilliped merus truncated on the mesiodistal margin, and the uropods extending beyond posterior margin of telson (cf. Rathbun 1901, fig. 15b–d; Biffar 1971, fig. 16c–e; Manning and Felder 1991, fig. 14a, b, e, f; Blanco and Liñero 1994, figs. 2a, b, 3c; see also Figures 1A, E, 3B). However, C. samba sp. n. can be distinguished from C. marginata in that in the new species the rostrum in adult specimens exceeds the eyestalks (Figure 1 (A)), whereas in C. marginata it is shorter than eyestalks (cf. Biffar 1971, fig. 16d). It is important to mention that in juveniles of C. marginata, the proportions of the length of the rostrum and of the eyestalk are inverted (ie the rostrum is longer than the eyestalk), as stated by Biffar (1971, p. 690) and illustrated by Manning and Felder (1991, p. 782, fig. 14a) in the drawing of a female syntype of this species. The two species can also be distinguished by the different proportion in length of the antennular peduncle to the antennal peduncle, slightly shorter in C. samba sp. n. (Figure 1A) but much shorter in C. marginata (cf. Biffar 1971, fig. 16d). The new species differs from C. marginata in the shape of the third maxilliped merus inferior margin, being rounded in C. samba sp. n. (Figure 1E) but straight and forming a right angle in C. marginata (Rathbun 1901, fig. 15c; Biffar 1971, fig. 16c; Manning and Felder 1991, fig. 14b).
Comparisons between C. samba sp. n. and the non-western Atlantic species of the genus indicate that the new species can be easily separated from C. brachytelson and C. oblonga by a combination of characters, including: (i) antennular peduncle shorter than antennal peduncle (vs antennular peduncle longer than antennal peduncle in C. brachytelson and C. oblonga); (ii) antennal peduncle with penultimate article 1.2 times longer than distal article (vs penultimate article 1.5 times longer than distal article in C. brachytelson); (iii) first pleopod of male present and composed of two articles (vs first pleopod of male absent in C. brachytelson but present and composed of only one article in C. oblonga); and (iv) lateral margins of telson non parallel (vs lateral margin parallel in C. brachytelson and converging posteriorly in C. oblonga) (cf. Sakai 2002, fig. 21b, c; Le Loeuff and Intes 1974, fig. 9a, q, r; see also Figures 1A, 3B, C).
description: Published as part of Hernáez, Patricio & Souza-Filho, Jesser F., 2025, A new species of the callianassid ghost shrimp genus Cheramoides Sakai, 2011, from Brazil (Crustacea: Decapoda: Axiidea), pp. 241-252 in Journal of Natural History 59 (5 - 8) on pages 243-250, DOI: 10.1080/00222933.2024.2437498, http://zenodo.org/record/14765156