Curculionichthys coxipone, Roxo, Fabio F., Silva, Gabriel S. C., Ochoa, Luz E. & Oliveira, Claudio, 2015

Roxo, Fabio F., Silva, Gabriel S. C., Ochoa, Luz E. & Oliveira, Claudio, 2015, Description of a new genus and three new species of Otothyrinae (Siluriformes, Loricariidae), ZooKeys 534, pp. 103-134 : 112-117

Taxon classification Animalia Siluriformes Loricariidae

Curculionichthys coxipone sp. n. Figure 9; Table 1

Hisonotus sp. 5 - Roxo et al. 2014a: 9(8) e105564 (phylogenetic relationships).

Holotype.

MZUSP 117380, female, 29.0 mm SL, Mato Grosso State, municipality of Cuiabá, tributary of Rio Aricá Mirim, Rio Cuiabá drainage, Rio Paraguai basin, 15°46'03"S, 55°30'44"W, September 2011, coll. Mehanna MN, Ferreira AT.

Paratypes.

All from Brazil, Mato Grosso State, Rio Cuiabá drainage, Rio Paraguai basin. LBP 5061 (3 females, 21.7−30.0 mm SL, 2 males, 25.8−27.9 mm SL), municipality of Cuiabá, tributary of Rio Aricá Mirim, 15°46'03"S, 55°30'44"W, 07 September 2007, coll. Mehanna MN, Ferreira AT. LBP 5062 (3 females, 22.5−28.7 mm SL), municipality of Cuiabá, tributary of Rio Aricá Mirim, 15°46'03"S, 55°30'44"W, 07 September 2007, coll. Mehanna MN, Ferreira AT. LBP 5069 (9 females, 22.5−29.6 mm SL, 3 males, 25.6−26.9 mm SL, 1 c&s, sex not determined, 25.6 mm SL), municipality of Cuiabá, tributary of Rio Aricá Mirim, 15°46'03"S, 55°30'44"W, 08 November 2007, coll. Mehanna MN, Ferreira AT. LBP 5646 (11 females, 21.8−28.8 mm SL, 7, males, 24.9−28.0 mm SL, 3 c&s, sex not determined, 26.8−28.2 mm SL), municipality of Cuiabá, tributary of Rio Aricá Mirim, 15°46'03"S, 55°30'44"W, 11 November 2007, coll. Mehanna MN, Ferreira AT. NUP 2264 (6 females, 18.2−25.3 mm SL, 6 males, 23.4−23.7 mm SL), municipality of Chapada dos Guimarães, Córrego São Joaquim, 14°46'53"S, 55°39'57"W, 26 March 2014, coll. NUPELIA´s team. NUP 14947 (6 females, 21.2−25.1 mm SL, 21.9−25.0 mm SL, 3 juveniles), municipality of Chapada dos Guimarães, Córrego Laranjinha, tributary of Rio Manso, 14°57'18"S, 55°41'15"W, June 2013, coll. NUPELIA´s team. NUP 16442 (6 females, 23.4−28.7 mm SL, 1 c&s sex not determined, 28.7 mm SL), collected with holotype.

Diagnosis.

Curculionichthys coxipone differs from all congeners by having a higher number of vertebrae 29−30 (vs. 28 in all other species of Curculionichthys ). The new species differs from all congeners, except Curculionichthys sabaji and Curculionichthys paresi by having the cleithrum with an area free of odontodes, Fig. 4B (vs. cleithrum completely covered with odontodes, Fig. 4D−F). The new species further differs from all congeners, except Curculionichthys oliveirai by having the anterior profile of the head rounded (vs. pointed); from Curculionichthys piracanjuba , Curculionichthys sagarana , and Curculionichthys oliveirai by having lower lip with some papillae arranged in a medial longitudinal series extending posterior to dentaries through middle portion of lower lip (vs. lower lip with all papillae randomly distributed); from Curculionichthys insperatus and Curculionichthys oliveirai by having the caudal fin hyaline, with one dark stripe extending from the caudal peduncle base to the middle caudal fin rays, and dark chromatophores irregular distributed almost forming one band, Fig. 5D (vs. caudal fin hyaline, with dark blotch limited to caudal peduncle base, Fig. 5B and E, respectively); from Curculionichthys paresi by lacking contrasting dark-brown geometric spots on the anterior region of the body (vs. presence of dark-brown geometric spots); from Curculionichthys sabaji by lacking several dark-brown spots distributed on the body (vs. presence of dark-brown spots); from Curculionichthys oliveirai and Curculionichthys coxipone by having the anterior profile of the head pointed (vs. rounded); from Curculionichthys oliveirai by having 7−9 lateral abdomen plates (vs. 4−5 lateral abdomen plates); from Curculionichthys paresi by having more dentary teeth 9−13 (vs. 4−7); from Curculionichthys oliveirai by having 6−9 lateral abdomen plates (vs. 4−5 lateral abdomen plates); from Curculionichthys sagarana by absence of one unpaired platelets on dorsal portion of caudal peduncle (vs. presence of one unpaired platelets on dorsal portion of caudal peduncle, Fig. 6); from Curculionichthys piracanjuba by having some papillae on the lower lip arranged in a medial longitudinal series extending posterior to the dentaries through the middle portion of lower lip (vs. lower lip with all papillae randomly distributed) and by not having hypertrophied odontodes on the snout tip (vs. hypertrophied odontodes on the snout tip); from Curculionichthys insperatus by having small, inconspicuous odontodes forming rows on the head and trunk (vs. large, conspicuous odontodes forming rows on the head and the trunk). Additionally, Curculionichthys coxipone is distinguished by having a shorter interorbital distance (33.8−37.8% of HL, vs. 27.4−33.6% of HL in Curculionichthys sagarana ); a shorter dorsal fin spine (14.9−24.8% of SL, vs. 25.2−27.0% of SL in Curculionichthys paresi ); a shorter pectoral fin spine (19.0−25.2% of SL, vs. 27.0−30.1% of SL in Curculionichthys paresi ); a longer mandibular ramus (8.2−12.5% of HL, vs. 6.0−8.0% of HL in Curculionichthys paresi ); and a shorter snout (48.0−58.9% of HL, vs. 67.7−72.7% of HL in Curculionichthys piracanjuba ; 67.0−75.3% of HL in Curculionichthys luteofrenatus ).

Description.

Morphometric and meristic available in Table 1. Small loricariid; bigger specimen examined reached 29.9 mm SL. In lateral view, dorsal profile of head convex from snout tip to posterior margin of parieto supraoccipital, and straight to dorsal fin origin. Dorsal profile of trunk slightly concave and descending from dorsal fin origin to end of dorsal fin base, straight to caudal peduncle. Ventral profile concave from snout tip to opercular region; convex from opercular region to anal fin origin; concave to caudal fin insertion. Greatest body depth at dorsal fin origin. Greatest body width at opercular region, gradually decreasing towards snout and caudal fin. Cross-section of trunk and caudal peduncle almost ellipsoid; rounded laterally and almost flat dorsally and ventrally.

Head rounded in dorsal view; snout round to slightly pointed, its tip rounded, elongated (48.0−52.9% HL), slightly convex between orbits. Dorsal and ventral series of odontodes along anterior margin of snout completely covering its tip; odontodes at same size than remaining ones on head. Odontodes on head and trunk hypertrophied and arranged in longitudinal rows (most prominent on head). Eyes moderately small (12.0−16.4% HL), dorsolaterally positioned. Lips roundish with papillae arranged in a medial longitudinal series extending posterior to dentaries through middle portion of lower lip. Lower lip larger than upper lip; its border fringed. Maxillary barbel present; joined to lower lip. Teeth slender and bicuspid; medial cusp larger than lateral cusp. Premaxillary teeth 7−15. Dentary teeth 7−16.

Dorsal fin ii, 7; dorsal fin spinelet short and V-shaped (Fig. 10A); dorsal fin lock functional; dorsal fin origin slightly posterior to pelvic fin origin. Tip of adpressed dorsal fin reaching anal fin insertion. Pectoral fin i, 6; its tip reaching beyond pelvic fin insertion when depressed. Presence of pectoral axillary slit between pectoral fin insertion and lateral process of cleithrum variable; absent in some specimens. Pectoral spine supporting odontodes on ventral, anterior and dorsal surfaces. Pelvic fin i, 5; tip of pelvic fin unbranched ray almost reaching anal fin origin when depressed in females and reaching anal fin origin in males. Pelvic fin unbranched ray with dermal flap along dorsal surface in males. Anal fin i, 5; distal margin slightly convex. Caudal fin i, 7-7, i; slightly emarginate; both unbranched rays of same size. Adipose fin absent. Total vertebrae 29−30 (1 c&s 29 vertebrae and 3 c&s 30 vertebrae).

Body covered with bony plates, except above head, around pectoral and pelvic fin origins and on dorsal fin base. Cleithrum and coracoid partially exposed. Arrector fossae partially to completely enclosed by ventral lamina of coracoids. Abdomen entirely covered by plates (Fig. 10B); lateral plates series with elongated and large plates formed by two lateral plate series, similar in size; median plates formed by six to seven irregular plate series reaching anal shield and lateral plate series; anal plates series covered by large square plates. Body entirely covered laterally by plates (Fig. 10C); mid-dorsal plates poorly developed and reaching middle of dorsal fin base; median plates series continuous in median portion of body; mid-ventral plates reaching of caudal peduncle origin.

Parts of dorsal head bone plates presented in Fig. 10D. Snout tip formed by one pair of rostral rectangular-shaped plates (r). Nasal (n) almost rectangular forming anterior medial nostril margin in contact posteriorly with frontals (f) and anteriorly and laterally with pre-nasals (pn). Pre-nasals (pn) positioned posteriorly of rostral plates (r), formed by two large and one small oval-shaped plates, and one elongate oval shaped between nares. Top of head composed by compound pterotic (cpt), parieto supraoccipital (soc) and frontal (f), largest bones of head, and prefrontal (pf) and sphenotic (sp). Compound pterotic (cpt) fenestrated randomly distributed. Posterior rostrum plates pr1-pr2 small, first triangular and second rectangular-shaped; pr4-pr3 largest, and rectangular shaped. Infraorbital plate series complete (io1-io5), present just above posterior rostrum series, all covered by latero-sensory canal system; io2 largest and io5 smallest; io3, io4 and io5 forming inferior orbital margin of eyes; preopercle (pop) elongated and rectangular, covered by latero-sensory canal; preopercle present under io4, and upper cp1, cp2 and op. Supra-opercular plate (spop) present just above preopercle, covered by latero-sensory canal. Subocular cheek plates (cp1-cp2) and opercle (op) form posterior lateral margin of head.

Color in alcohol. Ground color of dorsal and ventral region of head and trunk pale yellowish; dorsal portion darker than ventral. Four dark saddle along dorsal portion of body: first at dorsal fin origin; second at end of dorsal fin; third at middle of caudal peduncle; and fourth at end of caudal peduncle. Unpigmented portion of snout appears as two hyaline parallel stripes from rostral plate to nares. Dorsal, pectoral, and pelvic fins hyaline. Caudal fin hyaline, with dark stripe extending from caudal peduncle base onto base of median caudal fin rays, and with dark chromatophores forming one large band.

Sexual dimorphism. Adults males have a papilla in urogenital opening (vs. absent in females); and have an unbranched pelvic fin ray supporting a dermal flap along its dorsal surface. Both sexes have a membrane on the anal opening; however, this membrane is more developed in females than in males, covering almost the entire urogenital opening (see reference to this last character in Roxo et al. 2014b).

Distribution.

The new species Curculionichthys coxipone is known from Rio Cuiaba drainage, Rio Paraguay basin, Mato Grosso State in Brazil (Fig. 8).

Etymology.

The specific name “coxipone” refers to the Coxiponé indigenous people who inhabit the margins of Rio Cuiabá, near to the municipality of Cuiabá in Mato Grosso State, Brazil. A noun in opposition.

Comparative remarks.

Curculionichthys coxipone is similar in external morphology with Curculionichthys oliveirai from Rio Ivaí, upper Rio Paraná basin. However, the new species Curculionichthys coxipone can be distinguished from Curculionichthys oliveirai by having the cleithrum with an area free of odontodes, a higher number of vertebrae 29−30 and by a hyaline caudal fin, with one dark stripe extending from the caudal peduncle base to the median caudal fin rays, and for dark chromatophores irregular distributed almost forming one band. Furthermore, the presence of a higher number of vertebrae appears to be unique to Curculionichthys coxipone .