Pohleus heptacanthus (Bell, 1836) gen. nov. et, 2020

Colavite, Jessica, Windsor, Amanda M. & Santana, William, 2020, A new genus for Pericera septemspinosa Stimpson, 1871 and Pericera heptacantha Bell, 1836 (Crustacea, Brachyura, Majoidea), based on morphology and molecular data, Zoosystematics and Evolution 96 (1), pp. 205-216 : 205

Pohleus heptacanthus (Bell, 1836) gen. nov. et comb. nov. Fig. 5C, D

Pericera heptacantha Bell, 1836: 173 [type locality: Puerto Potrero, Central America, 23.7 m depth; type material: syntypes, 1 male (non-extant), 1 female (OUM 13764)] - Bell 1836b: 61, pl. 12, fig. 6 and 6r-u; White 1847: 10; A. Milne-Edwards 1873: 55.

Macrocoeloma heptacantha - Miers 1886: 79, 81.

Macrocoeloma heptacanthum - Rathbun 1898a: 576; 1925: 473, pl. 173, fig. 1; pl. 269, fig. 8-11, text-figs 133, 134; Garth 1958: 415; Di Mauro 1982: 170; Ng et al. 2008: 119.

Lectotype

(Here designated).

Costa Rica • 1 female, cl: 35 mm, cw: 43 mm; Central America, Puerto Potrero, 23.7 m depth; H Cumming leg. (OUM 13764) (Fig. 5C, D ).

Material examined.

Mexico • 1 juv. female; Off Cape San Lucas, R/V Albatross, stn 2829, 22°52'00"N, 109°55'00"W, RKY leg., 56.6 m depth, 74.1 °F; 01 May 1888, M J Rathbun det. (USNM 21933 illustrated). Panama • 1 juv. female; Panama Bay, R/V Albatross, stn 2798, 8°10'30"N, 78°50'30"W, 114.6 m depth; 05 Mar1888, M J Rathbun det. (USNM 21932).

Diagnosis.

Rostrum width less than one-third of interorbital length, bifurcated, base elongated, fused, diverging abruptly forming a Y-shape, ending in acute tip. Pleonal somite II with one spine or tubercle. Merus of second pereopod smooth.

Description based on female lectotype

(male characters modified from Bell 1836b). Cephalothorax and appendages slightly covered with short, velvet-like pubescence. Carapace subglobose wider than long, convex, with long lines of hooked and simple setae in all regions. Rostrum short, less than one-third of interorbital length, bifurcated, base elongated, fused, diverging abruptly forming a Y-shape, ending in acute tips. Interorbital region slightly depressed medially. Hepatic region broad. One metagastric spine. Four long, strong, conical lateral spines (two in each branchial region), in line with cardiac spine. One short intestinal spine. Orbital region very prominent, eyes completely protected when retracted, ocular peduncle visible when not retracted. Pre-orbital spine directed upwards, slightly curved on tip, longer than post-orbital spine, ventral margin of pre-orbital spine with small crenulation; post-orbital spine curved upwards.

Antennular fossae wider than long, margins smooth. Interantennular septum elongate, laterally compressed, forming distinct ventrally-directed lobe. First and second antennal articles fused to epistome, with suture between antenna and epistome visible, antennal gland opening near suture line. Basal article of antenna with two spines, not visible in dorsal view: proximal spine smallest. Antennal flagella longer than rostral spines, behind rostrum in dorsal view.

Epistome anterior margin narrower than antennular fossae, smooth, posterior margin slightly depressed. Buccal field sub-rectangular, narrower at posterior edge with one acute spine in anterolateral angle aligned with antennal spines. Third maxillipeds covering buccal frame when closed, leaving a small gap between ischia. Exopod long, nearly reaching distal margin of merus. Pterygostomial region subtriangular, slightly inflated, separated from subhepatic region by marked groove, with one long, strong spine slightly curved upwards on medial margin, visible in dorsal view.

Male chelipeds equal, longer than pereopods; covered with sparse granulation, unarmed. Dactylus arched in adult males, leaving small gap between fingers, distinctly shorter than palm. Cutting edges with sub-equal teeth in distal half, one distinct proximal tooth in larger males; distal half with light brown colour in fixed specimens. Pereopods short, slender, cylindrical. P2 longest; P3-P5 progressively decreasing in length. Dactylus slightly curved, covered with short setae.

Female chelipeds equal, longer than pereopods, slender and smooth. Dactylus arched in adult, shorter than palm, sub-equal teeth in distal half. Pereopods, slender, cylindrical. P2 longest, P3-P5 progressively decreasing in length. Dactylus slightly curved, shorter than propodus, smooth ventrally, with corneous tips.

Male thoracic sternites I-IV fused, broadly triangular, smooth, anterior half declivous in ventral view. Telson fully fitted to cavity, anterior margin smooth.

Female pleonal somites I-VI markedly arched, telson free, transversally oval, with a row of setae on margin and one small spine in first somite. Male pleon rather prominent, pleonal somites I-VI, telson free, somite II with a mesial tubercle. Somite III with slight elevations. Somite VI longest, with a mesial tubercle and a small projection each side.

Colour in life.

Light brown, covered with darker hair, first pair of pereopods reddish (Bell 1936b).

Type locality.

Costa Rica, Central America, Puerto Potrero, in sand at a depth of 23.7 m.

Geographic distribution.

Eastern Pacific: Mexico (Cape San Lucas), Costa Rica (Guanacaste) and Panamá (Panama Bay) (Fig. 4 ).

Remarks.

Bell (1836) described Pericera heptacantha , based on two specimens as syntypes, one male and one female. The male syntype is considered lost and the female is deposited in the dry crustacean collection of the Oxford University Museum (OUM 13764) ( Di Mauro 1982). Thus, the female syntype (OUM 13764) is here designated as the lectotype of Pericera heptacantha since it is the only specimen from the type series remaining (Fig. 5C, D ). The locality Puerto Potrero in Central America probably refers to the Puerto Potrero, Guanacaste, in Costa Rica. Rathbun (1937: 136) examining Lithadia cumingii Bell, 1855, a species described from the same locality by Bell (1855), referred to the type locality as from Potrero, Costa Rica, the same case as for Pohleus heptacanthus gen. nov. et comb. nov.

Figures

Figure 4. Geographic distribution Pohleus heptacanthus (Bell, 1836) gen. nov. et comb. nov.; orange circles = distribution based on examined material; green star = type locality and Pohleus septemspinosus (Stimpson, 1871) gen. nov. et comb. nov.; red circles = distribution based on examined material; yellow star = neotype locality.

Figure 5. Pohleus septemspinosus (Stimpson, 1871) gen. nov. et comb. nov. A, B. female (MNHN IU 2013 - 32682). Pohleus heptacanthus (Bell, 1836) gen. nov. et comb. nov.; C, D. female lectotype (OUM 13764). A, C. habitus; B, D. ventral view. Note the spine on merus of the second pereopod (white arrow). Scale bars: 10 mm.