Pachycheles meloi Ferreira & Tavares 2017, sp. nov.

Pachycheles meloi sp. nov.

(Figs. 1 A, C; 2A–N; 3A, B)

Pachycheles riisei.— Moreira 1920: 132.— Melo 1999: 240 [geographic distribution].— Rodríguez et al. 2005: 557 [geographic distribution].— Ferreira 2009: 60 [geographic distribution].— Santos et al. 2012: 158 [geographic distribution].— Ferreira & Melo, 2016: 183 [geographic distribution]. [not Pachycheles riisei (Stimpson, 1859)].

Type material. Holotype: male, cl 4.2, cw 4.5. Brazil, Espírito Santo, Trindade Island, Praia da Calheta, 20°30’29.5’S, 29°18’37.0”W, JB Mendonça coll., 21 June 2016, 12.5 m (MZUSP 34901). Paratypes: 1 male, cl 4.8, cw 5.2, 1 ovigerous females, cl 4.4, cw 4.8, Trindade Island, Laje da Ponta Noroeste, 20°29’57.8’S, 29°20’39.2”W, JB Mendonça coll., 16 July 2012, 15.3 m (MZUSP 34896); 1 male, cl 5.4, cw 5.6, 1 ovigerous female, cl 4.5, cw 4.8, Trindade Island, Parcel das Tartarugas, 20°31’01.3’S, 29°17’56.9”W, JB Mendonça coll., 11 July 2012, 14.5 m (MZUSP 34897); 1 male, cl 4.0, cw 4.2, 1 female, cl 4.1, cw 4.3, Trindade Island, Ponta Norte, 20°29’18.7”S, 29°20’18.3”W, JB Mendonça coll., 0 3 July 2012, 15.6 m (MZUSP 34899); 1 male, cl 4.2, cw 4.3, 1 ovigerous female, cl 4.8, cw 5.3, Trindade Island, Enseada dos Portugueses, SECON, 20°30’20.9”S, 29°18’43.7”W, JB Mendonça coll., 11 November 2014, 11 m (MZUSP 34900); 1 male, cl 2.1, cw 2.2, Trindade Island, Orelhas, 20°29’40.2”S, 29°20’32.9”W, JB Mendonça coll., 16 May 2014, 10.4 m (MZUSP 34893); 1 male, cl 4.6, cw 4.9, 1 ovigerous female, cl 4.6, cw 5.0, Trindade Island, Parcel, Praia das Tartarugas, 20°31’01.3”S, 29°17’56.9”W, JB Mendonça coll., 30 April 2014, 9.8 m (USNM 1441799).

Other material examined. Brazil: Trindade Island, Ponta Norte, 20°29’18.7’S, 29°20’18.3”W, JB Mendonça coll., 0 1 April 2014, 11.5 m: 3 males, 1 ovigerous female (MZUSP 34837); Ibidem, 0 3 July 2016, 15.6 m: 3 males, 4 females, 1 ovigerous female (MZUSP 34883); Ponta Noroeste, 20°29’46.4’S, 29°20’35.4”W, JB Mendonça coll., 0 4 July 2012, 11.6 m: 1 male, 1 female, 1 ovigerous female (MZUSP 34839); Ponta do Monumento, 20°30’10.3’S, 29°20’32.6”W, JB Mendonça coll., 0 2 November 2014, 14.9 m: 3 males, 4 females, 3 ovigerous females, 2 juveniles (MZUSP 34876); Ilha da Racha, 20°30’26.5’S, 29°20’48.0”W, JB Mendonça coll., 0 3 July 2015, 23 m: 1 male (MZUSP 34828); Orelhas, 20°29’40.2’S, 29°20’32.9”W, JB Mendonça coll., 30 June 2012, 14.4 m: 5 males, 4 females, 2 ovigerous females (MZUSP 34835); Ibidem, 0 1 July 2016, 9.2 m: 1 male (MZUSP 34885); Enseada dos Portugueses, Praia da Calheta, 20°30’37.6’S, 29°18’28.1”W, JB Mendonça coll., 26 October 2014, 9.9 m: 1 male (MZUSP 34843); SECON, 20°30’20.9’S, 29°18’43.7”W, JB Mendonça coll., 18 July 2013, 12.2 m: 1 male (MZUSP 34846); SECON, 20°30’20.9’S, 29°18’43.7”W, JB Mendonça coll., 11 November 2014, 11 m: 2 males, 1 female, 3 ovigerous females (MZUSP 34882); Praia dos Portugueses, Rampa Nova, 20°30’17.7’S, 29°18’56.7”W, JB Mendonça coll., 23 April 2014, 10.7 m: 1 male (MZUSP 34866); Praia das Tartarugas, 20°31’01.3’S, 29°17’56.9”W, JB Mendonça coll., 30 April 2014, 9.8 m: 1 male, 3 females (MZUSP 34887); Parcel das Tartarugas, 20°31’01.3’S, 29°17’56.9”W, JB Mendonça coll., 11 July 2012, 14.5 m: 3 males, 2 females, 2 ovigerous females (MZUSP 34845); 20°31’10.4’S, 29°17’58.4”W, natural pool, intertidal, JB Mendonça coll., 19 June 2016, 1 m: 1 male (MZUSP 34890); Praia do Lixo, 20°31’29.8’S, 29°19’43.9”W, JB Mendonça coll., 25 October 2014, 13.7 m: 1 male (MZUSP 34892); Enseada da Cachoeira, Farrilhões, 20°31’22.4’S, 29°19’52.0”W, JB Mendonça coll., 20 April 2012, 11.8 m: 1 male, 2 ovigerous females (MZUSP 34844); Ibidem, 20 June 2012, 11.8 m: 1 male, 1 ovigerous female (MZUSP 34825); Ibidem, 0 2 July 2012, 16.3 m: 2 males, 1 female (MZUSP 34842); Praia das Cabritas, left corner, 20°29’32.0’S, 29°19’46.6”W, JB Mendonça coll., 28 April 2014, 9.2 m: 4 males, 1 female, 2 ovigerous females (MZUSP 34841); Enseada do Príncipe, Paredão, 20°31’22.4’S, 29°19’52.0”W, JB Mendonça coll., 0 9 July 2013, 19.5 m: 2 males, 1 female (MZUSP 34879); Ilha Sul, 20°31’34.3’S, 29°19’27.9”W, JB Mendonça coll., 10 July 2015, 22.2 m: 1 male, 1 ovigerous female (MZUSP 34830); Martin Vaz Archipelago, Martin Vaz Island, 20°30’45.7’S, 29°18’21.9”W, JB Mendonça coll., 24 July 2013, 12.3 m: 1 male, 1 ovigerous female (MZUSP 34865).

Type locality. Brazil, Espírito Santo, Trindade Island, Praia da Calheta, 20°30’29.5’S, 29°18’37.0”W. Distribution. Currently endemic to the remote oceanic archipelago of Trindade and Martin Vaz, South Atlantic Ocean, between 1 and 23 m.

Description. Carapace subcircular, broader than long in males and females, slightly rugose dorsally. Frontal region poorly depressed. Frontal width slightly less than half of maximum carapace width. Frontal margin distinctly granular, double, sinuous in dorsal view, trilobate in frontal view, devoid of setae; median lobe prominent, slightly overreaching lateral lobes; lateral lobes broad, rounded. Outer orbital angle well defined, subtriangular. Carapace lateral margin poorly-defined, wrinkled. Protogastric, gastric and epibranchial regions slightly swollen. Cervical groove well defined, ending in distinct, smooth notch anteriorly. Carapace posterolateral surface with pilose rugae, posterior margin nearly straight, devoid of setae. Branchiostegite distinctly rugose, split into calcified plates of different sizes: one large anterior, one small posterior, and several much smaller plates. Branchiostegal margin not pubescent.

Thoracic sternite 3 median lobe broad anteriorly, gently rounded, unarmed; lateral lobes narrow, tip rounded, as long as median lobe. Sternites 4–7 broad, sutures between sternites incomplete, distinct only laterally. Sternite 8 anterior margin convex, posterior margin concave.

Ocular peduncle short. Orbit with smooth margin. Cornea large, rounded, dilated.

Antennular basal segment large, with poorly developed distomesial spine. Segments 2 and 3 unarmed, subcylindrical; segment 3 broadened distally. Dorsal flagellum composed of approximately 15 articles; ventral flagellum with 4 flattened articles decreasing in size distally.

Antennal segments slightly rugose, short. Coxa subtriangular, membranous dorsally, calcified ventrally. Basisischium 2/3 as long as merus. Merus distinctly granular with well-developed distomesial tubercle. Carpus half of total length of merus, mesial surface poorly granular. Flagellum long, slender.

Mxp 3 dorsal surface distinctly rugose. Exopod oblong, reaching about half of total length of merus; flagellum well developed. Ischium lateral lobe distinct, separated by deep V-shaped incision. Merus as long as ischium; mesial lobe broad, slightly upturned, tip rounded.

P1 slightly unequal in size in males and females, robust, scattered rugosae dorsally. Merus about 1/3 length of carpus; mesial lobe subtriangular, poorly-developed; 2 to 4 distal spines well developed ventrally. Carpus about half length of propodus; mesial margin with 1 to 3 lamelliform lobes; lateral margin distinctly rugosae, ending in acute, distal spine. Dorsal surface of carpus rugosae, more intensely so near lateral margin. Carpus and propodus distinctly grooved along lateral margins. Palm slightly swollen. Fixed finger as long as dactylus; cutting edge with large proximal tubercle. Dactylus cutting edge with large, proximal tubercle; tip curved, crossing with that of fixed finger. Cutting edges of fingers devoid of setae. Major P1 fingers leaving narrow hiatus when closed. Fingers of minor P1 closing tightly, furrowed along cutting edges.

Walking legs decreasing in size from P2–4, robust, slightly rugose, fringed with dense, long setae, especially on carpi and propodi. P2 carpus slightly longer than half length of merus. P3 carpus about half length of merus. P4 carpus slightly shorter than half length of merus. P2–3 carpi about half length of P2–3 propodi, respectively. P4 carpus slightly shorter than propodus. P2–4 carpi with two low, longitudinal, parallel carinas dorsally; carpi with one well developed, dorsodistal spine. P2–4 propodi with four spines on ventral surface: two medially aligned, two on distal corner near articulation with dactylus. P2–3 dactyli about half length of P2–3 propodi, respectively. P4 dactylus about 2/3 length of propodus; dactylus with longitudinal row of 5 spines ventrally. P5 short, ischium 1/3 of length of merus; merus as long as carpus; propodus about 1/3 of length of carpus; dactylus about 1/3 of length of propodus.

Male and female abdomen subrectangular, somites smooth dorsally, lateral margins with long, plumose setae. Male gonopods well developed on somite 2, endopodite about 2/3 shorter than protopodite, broad medially, slightly tapering distally, round tipped. Exopodit absent (Fig. 3 A, B); female pleopods well developed on somites 3–5. Uropods broad, reaching to distal margin of telson. Telson nearly smooth dorsally, broader than long, subdivided into 5 plates.

Size. Largest male: cl 5.4, cw 5.6 (MZUSP 34897). Largest female: cl 5.1, cw 5.5 (MZUSP 34839). Smallest ovigerous female cl 2.8, cw 3.0 (MZUSP 34877).

Coloration. Carapace, ocular peduncle, Mxp 3, P1 and abdomen dark carmine. Carapace with one large, white spot at each epibranchial angle and one tiny, white spot next to each cardiac region; outer orbital angle white. Antenna white with reddish spots. Branchiostegite with median third dark carmine, anterior and posterior thirds white. P1 with white spots on merus distomesial margin, carpus mesial margin and distolateral angle. Tips of fingers white. P2–4 with white horizontal stripes intercalated with carmine or orange on merus, carpus and propodus. Abdominal segments dark carmine with scattered white spots. Thoracic sternum, uropods and telson white (Fig. 1 A). Small specimens orangish in color (Fig. 1 B).

Habitat. Frequently associated with calcareous algae (Fig. 1 C) and mostly collected along with Petrolisthes amoenus; 1–23 m depth.

Etymology. The species is named in honor of our colleague and friend Gustavo Augusto Schmidt de Melo (MZUSP) in recognition of his outstanding contributions to the taxonomy of the Brazilian decapod crustaceans.

Remarks. Pachycheles meloi sp. nov. from the remote oceanic archipelago of Trindade and Martin Vaz is closely similar to Pachycheles riisei (Stimpson, 1858) (Figs. 1 D, 4A–E), known from the inner continental shelf between Florida (USA) and São Paulo (Brazil) (Ferreira & Melo 2016). However, Pachycheles meloi sp. nov. can be easily separated from P. riisei in having: (1) a pair of developed, male pleopods on the second abdominal somite, Fig. 3 A (versus second male pleopods absent in P. riisei); (2) the carapace width slightly narrower in males and females, Fig. 2 A (versus carapace width slightly broader in P. riisei, Fig. 4 A); (3) the carapace, antennal peduncle, and P1–4 more roughly ornamented by conspicuous rugae and granules, Fig. 2 A, E, F, J–L (versus carapace, antennal peduncle, and P1–4 less rugosae and granular in P. riisei, Fig. 4 A, E); (3) the margin of the frontal median lobe margin with well-developed, acuminate granules, Fig. 2 A (versus small, rounded granules in P. riisei, Fig. 4 A); (4) the lateral surface of the P1 carpus with larger and denser tubercles in P. meloi sp. nov., Fig. 2 H, I (versus tubercles smaller and scattered distributed in P. riisei, Fig. 4 C, D); and (5) the thoracic sternum subquadrate in shape, Fig. 2 M (versus thoracic sternum broader than long, especially posteriorly in P. riisei, Fig. 4 B).

Pachycheles meloi sp. nov. and P. riisei share similar coloration patterns. However, in P. meloi sp. nov. (Fig. 1 A, B) P1 and the abdomen are dark carmine with scattered white spots, whereas in P. riisei P1 is devoid of white dots and the abdomen white.

Pachycheles biocellatus (Lockington, 1878), is the Pacific analogue of P. riisei, known from Gulf of California to Ecuador (Haig 1960; García-Madrigal & Andréu-Sánchez 2009), and is hereafter compared to P. meloi sp. nov. The present new species differs from P. biocellatus in having: (1) the carapace markedly swollen (versus carapace more flattened dorsally in P. biocellatus); (2) the carapace front strongly projected, overreaching the cornea in dorsal view (versus front slightly prominent, not overreaching the cornea in P. biocellatus); (3) the ventral surface of P2–4 dactyli armed with a row of 5 spines (versus P2–4 dactyli armed with only 3 ventral spines in P. biocellatus); and (4) a pair of developed, male pleopods on the second abdominal somite (versus second male pleopods absent in P. biocellatus).

Pachycheles grossimanus (Guérin-Méneville, 1835) and P. rugimanus A. Milne-Edwards, 1880, from the Pacific and Atlantic sides of the Americas, respectively, although morphologically very different from P. meloi sp. nov. share with it the presence of one pair of gonopods devoid of the exopod.

Pachycheles meloi sp. nov. differs from P. grossimanus in the (1) broad carapace front (versus narrow front, subtriangular in dorsal view in P. grossimanus); (2) basal antennular segment with a poorly developed distomesial spine (versus basal segment with several distal spines in P. grossimanus); (3) third thoracic sternite rounded-tipped (versus sternite subtriangular distally in P. grossimanus); (4) five-plated telson (versus seven-plated telson in P. grossimanus).

In contrast to P. rugimanus, an inhabitant of the continental shelf from North Carolina (USA) southward down to Pernambuco (Brazil) (Coelho 1964; Coelho et al. 2007; Ferreira & Melo 2016), P. meloi sp. nov. can be readily recognized by the (1) carapace broader than long in males (versus as broad as long in males of P. rugimanus); (2) mesial margin of the antenna's basis-ischium and carpus granulate (versus basis-ischium and carpus armed with quite evident spines on the mesial margins in P. rugimanus); and (3) P1 carpus and propodus with superficial rugae dorsally (versus P1 carpus and propodus with distinct carina and tubercles dorsally in P. rugimanus).

Two other southwestern Atlantic species, P. laevidactylus Ortmann, 1892 and P. chubutensis Boschi, 1963, also present a pair of developed, male gonopods on the second abdominal somite. However, differently from P. meloi sp. nov. in which the second gonopod is devoid of exopodit, in P. laevidactylus and P. chubutensis the gonopod is provided with a well recognizable, subcylindrical exopodit.

In Pachycheles meloi sp. nov. the number of lobes on the mesial margin of the P1 carpus vary with the size of the specimens: young specimens have three, distinct lobes, whereas in full grown specimens the lobes are fused together into a single, large lobe. The branchiostegite is split into calcified plates of different sizes: one large anterior, one small posterior, and several much smaller plates variable in number.

Moreira (1920) first recorded Pachycheles riisei from the Trindade Island (as Pisosoma risei [sic]). His record was based on a single specimen (cl 6, cw 7) no longer available in the collections of the Museu Nacional, Rio de Janeiro. Subsequent references to P. riisei from Trindade are highly questionable as there are no voucher specimens for them and are all probably derived from the original record by Moreira (e.g., Melo 1999; Rodríguez et al. 2005; Ferreira & Melo, 2016). From over 95 specimens obtained in the recent years from Trindade all belonged to P. meloi sp. nov. Therefore, most probably all records of P. riisei to Trindade actually refer to P. meloi sp. nov.