Hypolobocera ituangoensis, Campos & Alexander, 2024

Campos, Martha R. & Alexander, Moises, 2024, A new species of freshwater crab of the genus Hypolobocera Ortmann, 1897 from Colombia (Crustacea: Decapoda: Pseudothelphusidae), including a key to the species of the genus distributed in Colombia, Zootaxa 5453 (2), pp. 282-290 : 283-286

Hypolobocera ituangoensis , new species

( Figs. 1–3 )

Material examined. Holotype: male (cl 12.8 mm, cw 20.6 mm), ICN-CR 3628. Colombia, Antioquia Department, Ituango Municipality, Vereda La Georgia, La Honda stream, elevation 1505 m, 7°13’14.9”N, 75°49’36”W, 14 Aug 2023, leg. M. Alexander. Paratypes: 3 males (cl 14.0, 13.1, 12.5 mm, cw 22.5, 21.0, 20.2 mm), ICN-CR 3629, same locality data as for holotype .

Diagnosis. First male gonopod with caudal ridge long, concave, thickened basally, ending in narrow ridge on lateral side; lateral lobe prominent, rectangular, thickened, external lateral margin straight with row of conspicuously acute spines, cephalic surface of lateral lobe with irregular rows of spinules; apex outline oval widened in mid-basal portion in distal view, cephalic border with prominent cephalic spine-like papilla, directed cephalically; mesial lobe sub-triangular in distal view. Third maxilliped with exopod 0.2 to 0.3 length of ischium. Orifice of efferent branchial channel semi-circular, and open.

Description of holotype. Carapace ( Fig. 1A ) with straight, narrow, shallow cervical grooves, ending some distance of lateral margin; antero-lateral margins with wide, shallow, depression behind outer orbital angle, with five papillae before cervical grooves; lateral margins with approximately 15 tubercles, diminishing in size posteriorly; postfrontal lobes oval; median groove shallow, wide; front lacking distinct upper border, frontal area regularly sloping downwards, bilobed in dorsal view, lower margin sinuous in frontal view, visible in dorsal view, conspicuously thickened with row of coalescent papillae; lower orbital margins each fringed with tubercles; epistome narrow, lower margin moderately arched, epistomial tooth conspicuously, sub-triangular, rounded distally; buccal frame sub-square; pterygostomial region pubescent, with papillae; thoracic sternum ovate, bent anteriorly ( Fig. 1B ). Third maxilliped with rounded angle on distal half of external margin of merus, exopod 0.25 times length of ischium ( Fig. 1E ). Orifice of efferent branchial channel semi-circular, open ( Fig. 1C ).

First pereopods heterochelous ( Fig. 1A ) right cheliped larger than left, merus with 3 crests as follows: upper crest with rows of tubercles of different sizes, internal lower crest with 2 tight rows of large tubercles, diminishing in size proximally, external lower crest with row of papillae; carpus with acute subdistal spine, followed by 5 rounded tubercles; palms of both chelipeds smooth, palm of larger (right) cheliped strongly swollen, fingers 1.2 length of palm, not gaping when closed, tips not crossing ( Fig. 1A, D ); palm of smaller cheliped moderately swollen, fingers of equal length of palm, slightly gaping when closed, tips not crossing. Walking legs (second to fifth pereopods) slender ( Fig. 1A ), dactyli each about 1.3 times as long as propodi, with 5 longitudinal rows of large spines diminishing in size proximally, arrangement of spines on dactylus of left second pereopod as follows: antero-lateral, antero-ventral rows each with 5 spines, and a proximal papilla, external row with 6 spines, postero-ventral, postero-lateral rows each with 4 spines.

Episternites sub-triangular, partially fused with sternites, suture lines well defined, extended to mesial region; sterno-abdominal cavity concave, midline of sternum short, deep, restricted to sternite VIII, sternites V, VI with a deep concavity that receive distal processes of G1; abdomen subtriangular, margin with fine pubescence, somites well-differentiated, suture lines nearly straight, first abdominal segment narrow, increasing in size towards 6; telson sub-triangular, margin smooth, pubescent; dorsal surface of carapace smooth, covered by small papillae, regions not well demarcated.

Gonopod 1 in caudal view ( Fig. 2A ) recurved in caudo-cephalic direction, with caudal ridge long, concave, thickened basally, ending in narrow ridge on lateral side. Lateral lobe ( Fig. 2A, C–E ) prominent, rectangular, thickened, external lateral margin straight with row of conspicuously acute spines, distal and proximal external margins rounded, caudal surface with some papillae, cephalic surface with irregular rows of spinules. Lateral side ( Fig. 2A ) with narrow notch sub-apical, mid-wide depression, sinuously on mid-basal portion. Marginal suture situated along caudal surface, slightly sinuous, rounded distally with conspicuous long and short setae along proximal portion. Mesial side ( Fig. 2A, C ) nearly concave with some setae near mid-portion of appendage. Apex outline ( Fig. 2F ) oval widened in mid-basal portion in distal view, caudo-lateral expanded into rounded projection, cephalic border with prominent spine-like papilla directed cephalically. Meso-caudal projection of spermatic channel ( Fig. 2F ) short, ending in acute papilla. Orifice of spermatic channel ( Fig. 2F ) surrounded by rows of spinules. Mesial lobe ( Fig. 2C, F ), sub-triangular in distal view, with caudal and cephalic sides concaves, projected as a semi-acute lobe on caudal surface.

Colouration. The freshly-alcohol preserved holotype is brown (near Mars Brown, 223A) with light specks (near Cinnamon, 123A) on the dorsal side of the carapace. The walking legs dorsally brown (near Mars Brown, 223A), ventrally light brown (near Mikado Brown, 121C). The chelae brown dorsally (near Mars Brown, 223A), light brown ventrally (near Buff, 124). The ventral surface of the carapace is light brown (near Sayal Brown, 223C).

Habitat. The specimens were found in the Honda Stream, located in the Quibral micro-watershed, which flows into the Ituango River. The Quibral micro-watershed is significant because it contains water recharge areas in the upper parts of the mountain system that are associated with the Nudo de Paramillo sub-region ( Ituango 2024). The specimens were collected by hand under the rocks and leaf litter in La Honda stream, in the middle of a secondary forest. The stream was surrounded by a gallery forest and the water was characterized as crystal clear with sandyclay and silty-clay soils with leaf litter on the margins.

Etymology. The species is named after the Municipio Ituango which is the type locality of the new species.

Remarks. Hypolobocera ituangoensis n. sp. shows similarity in the shape of the G1 to Hypolobocera murindensis Campos, 2003 (see Campos 2003: figs. 19A–E). The main distinguishing features between the two species for their G1 are (1) in H. ituangoensis n. sp. the lateral lobe is prominent, rectangular, and presents the same size on the distal and the proximal portion, its external lateral margin is straight, with row of conspicuously acute spines, and with irregular rows of spinules on the cephalic surface ( Fig. 2A, C–E ), whereas H. murindensis has the lateral lobe rectangular with the distal portion narrower than the proximal one; the external lateral margin is rounded and devoid of spines, the cephalic surface of the lateral lobe is lacking of spinules, and the lateral lobe is nearly convex in lateral view ( Campos 2003: fig. 19A–C, E); (2) in H. ituangoensis n. sp. the apex is oval widened in mid-basal portion in distal view, caudo-lateral expanded into rounded projection, the cephalic border has a prominent cephalic semi-acute spine-like papilla, directed cephalically ( Fig. 2F ), whereas in H. murindensis it is oval elongated in distal view, caudo-lateral expanded into widest, rounded projection, the cephalic border presents a row of tiny spinules, and a cephalic semi-acute papilla, directed apically ( Campos 2003: fig. 19B, C, F); (3) in H. ituangoensis n. sp. the mesial lobe is sub-triangular in distal view ( Fig. 2F ), whereas in H. murindensis it is semi-circular ( Campos 2003: fig. 19F). The two species also differed in the length of the exopod of the third maxilliped, which is 0.20 to 0.30 in H. ituangoensis n. sp. ( Fig. 1E ) and 0.20 in H. murindensis ( Campos 2003: fig. 18C); in H. ituangoensis n. sp. ( Fig. 1C ) the orifice of the efferent branchial channel is semi-circular; in H. murindensis is irregularly ovate ( Campos 2003: fig. 18D).

Figures

FIGURE 1. Hypolobocera ituangoensis n. sp., male holotype (cl 12.8 mm, cw 20.6 mm), ICN-CR 3628. A,habitus, dorsal view; B, frontal view of carapace; C, opening of left efferent branchial channel, external view; D, chela of large cheliped, external view; E, left third maxilliped, external view.

FIGURE 2. Hypolobocera ituangoensis n. sp., male holotype (cl 12.8 mm, cw 20.6 mm), ICN-CR 3628, first male gonopod. A,left first gonopod, caudal view; B, same, mesial view;C, same, cephalic view; D, same, lateral view; E, same, lateral lobe caudal view; F, apex distal view. 1, marginal suture; 2, caudal ridge; 3, lateral lobe; 4, spines; 5, spinules; 6, spine-like papilla; 7, mesial lobe; 8, meso-caudal projection of spermatic channel; 9 spermatic channel.

FIGURE 3. Hypolobocera ituangoensis n. sp., male holotype (cl 12.8 mm, cw 20.6 mm), ICN-CR 3628. A,habitus, dorsal view; B, habitus, ventral view.