Curculionichthys hera, Gamarra & Calegari & Reis, 2019

Gamarra, Suelen P., Calegari, Bárbara B. & Reis, Roberto E., 2019, A new species of Curculionichthys (Siluriformes: Loricariidae) from the north edge of the Brazilian Shield, lower Amazon basin, Neotropical Ichthyology 17 (2), pp. 1-9 : 2-8

Curculionichthys hera , new species

urn:lsid:zoobank.org:act:ABBB1465-4147-4B90-A15D-7E17A64D33B5

Figs. 1-3 ; Tab. 1

Holotype. MCP 52500, female, 25.1 mm SL, igarapé do Onça , tributary to rio Curuá-Una on road BR-163 between Belterra and Rurópolis, Belterra, Pará, Brazil, 3º33’35.3”S 54°52’09.2”W, elevation 80 m asl, 19 October 2016, R. E. Reis, B. B. Calegari, T. P. Carvalho, J. de Bogotá, C. Oliveira, J. Souza, and E. Cerdeira.

Paratypes. Brazil, Pará, rioAmazonas basin: MCP 51571, 70 , 14.6-25.5 mm SL + 2 cs, 24.0- 25.6 mm SL + 9 tissue samples; NUP 20539, 7, 18.8-22.7 mm SL ; AMNH 267150 , 7 , 18.1-23.3 mm SL ; MZUSP 123948 , 7 , 18.6-24.5 mm SL; all collected with the holotype . MCP 51600, 15 , 15.8-24.2 mm SL + 4 tissue samples, igarapé Moju, tributary to rio Curuá-Una on road BR-163 between Belterra and Rurópolis , Belterra , 3°25’05.8”S 54°54’46.7”W, elevation 67 m asl, 19 October 2016, R. E. Reis, B. B. Calegari, T. P. Carvalho, J. de Bogotá, C. Oliveira, J. Souza, and E. Cerdeira .

Genseq-2 coI. MCP 51600 (tissue tag 426); GenBank Accession Number MK 24168.

Diagnosis. Curculionichthys hera is distinguished from its congeners, except C. jumaorum and C. karipuna Silva, Roxo, Melo, Oliveira, 2016 by possessing a single rostral plate (vs. a pair of rostral plates); and from congeners except for C. jumaorum and C. sabaji Roxo, Silva, Ochoa, Oliveira, 2015 by having darkened tooth-crowns (vs. hyaline to light yellow tipped teeth). The new species is further distinguished from C. oliveirai ( Roxo, Zawadzki, Troy, 2014) , C. sabaji , C. tukana Roxo, Dias, Silva, Oliveira, 2017 , and C. luteofrenatus (Britski, Garavello, 2007) by the smaller prepelvic distance (42.0-45.6% vs. 46.3-46.8%, 46.0-48.5%, 46.2-47.3%, and 46.1-50.7% SL, respectively); from the above species and also from C. itaim Roxo, Dias, Silva, Oliveira, 2017 and C. jumaorum , by the smaller suborbital distance (10.3-16.4% vs. 21.7- 22.8%, 18.6-20.0%, 19.2-21.2%, 17.5-23.4%, 17.8-23.2%, and 17.6-22.6% HL, respectively). The new species also differs from C. coxipone Roxo, Silva, Ochoa, Oliveira, 2015 , C. sabaji , C. insperatus (Britski, Garavello, 2003) , C. paresi , and C. jumaorum by the number of premaxillary teeth (15-20 vs. 7-15, 7-13, 6-14, 6-10, and 25-30, respectively). Additionally, C. hera differs from C. coxipone , C. luteofrenatus , C. tukana , C. sagarana Roxo, Silva, Ochoa, Oliveira, 2015 , C. insperatus , and C. paresi by possessing fewer plates in the middle series of lateral plates (22-23 vs. 25-27, 25-26, 24-26, 24-25, 24-25, and 24-25, respectively). The new species further differs from C. insperatus , C. sabaji , C. paresi , and C. jumaorum by the number of dentary teeth (12-21 vs. 5-11, 5-12, 4-7, and 20-27, respectively); and from C. coxipone , C. oliveirai , and C. paresi by the smaller body depth at the dorsalfin origin (11.3-15.9% vs. 16.3-18.5%, 17.6-20.3%, and 16.9-20.7% SL, respectively). It is distinguished from C. sabaji , C. tukana , and C. itaim by a narrower head (52.2-60.9% vs. 61.8-64.8%, 66.4-69.0%, and 61.7-67.6% respectively); from C. coxipone , C. oliveirai , C. tukana , C. luteofrenatus , and C. itaim by the smaller distance between pectoral- and pelvic-fin origins (12.5-16.8 vs. 16.9-18.7%, 17.4-19.7%, 18.8-20.4%, 16.9-20.6%, and 17.3-23.1% SL, respectively); from C. oliveirai by the shallower caudal peduncle (5.5-9.2% vs. 10.4-10.8% SL); from C. jumaorum by having a longer first pelvic-fin unbranched ray (17.2-23.5% vs. 14.8-15.7% SL), and from C. karipuna by laking an irregular concentration of chromatophores that entirely cover the anal-fin origin and adjacent region (vs. pigmentation present around the anal-fin origin and adjacent region). The new species is also distinguished by the fewer lateral abdominal plates (4-5 vs. 6-7 in C. karipuna and C. luteofrenatus , 6-9 in C. sagarana and C. sabaji , 7-8 in C. tukana , C. scaius Calegari, Gamarra, Reis, 2018 , and C. itaim , and 7-9 in C. coxipone ). Finally, the new species is distinguished from C. sagarana , C. insperatus , C. coxipone , C. luteofrenatus , C. piracanjuba (Martins, Langeani, 2012) , and C. sabaji by having a single series of large plates in middle abdominal series (vs. three regular series of plates or small platelets irregularly arranged).

Description. Morphometric and meristic data in Tab. 1 . Dorsal profile of head straight to slightly concave at anterior snout, concave from that point to middle parietosupraoccipital, and straight to slightly concave from that point to dorsal-fin origin. Head profile triangular in dorsal and ventral perspective with pointed snout. Snout elongated (47.5-56.4% HL); region anterior to depressed nostrils with slight elevations. Dorsal profile of body sloped and descending from dorsal-fin origin to few plates before end of caudal peduncle. Ventral profile of body relatively straight from snout to caudal-fin origin. Greater body width at opercle or at cleithrum. Body deepest at dorsal-fin origin and shallowest right before end of caudal peduncle.

Body covered by plates, except around urogenital opening, lateral to pelvic fin, anterior to upper lip, and between lower lip and pectoral girdle. Median series of lateral plates with 22-23 plates; lateral line almost complete ending one plate anterior to caudal-fin origin. Mid-dorsal series with 6 or 7 plates, not surpassing end of dorsal-fin base. Two regular transverse rows of predorsal plates, in addition to nuchal plate. Abdomen completely covered by large plates. Four or five large plates in lateral abdominal series (n = 32). Median series of abdominal plates forming single series of large plates, sometimes paired at posterior portion, preceding single, large preanal plate. All abdominal plates bearing small odontodes. Head and body with odontodes uniform in size and distribution, except ventral and dorsal portion of snout tip with slightly hypertrophied and strongly curved odontodes ( Fig. 2 ). Cleithrum and coracoid entirely exposed on ventral surface and covered with odontodes. Rostral plate single, covering tip of snout both ventral and dorsally.

Eye positioned dorsolaterally. Dorsal margin of orbit slightly elevated. Iris operculum present. Lips rounded and papillose with small fleshy ridge immediately behind dentary. Barbel small and laterally positioned, distal portion free from lip margin. Lower lip not reaching pectoral girdle. Posterior border of lower lip crenulate. Teeth thin, bifid, with large leafshaped medial cusp and small lateral cusp.

Dorsal fin II,7; its origin slightly posterior to vertical through end pelvic-fin base. Dorsal-fin spinelet V-shaped, locking mechanism functional. Pectoral fin I,6; pectoral-fin spine long and somewhat slender. Tip of pectoral-fin spine almost reaching to end of first pelvic-fin ray; approximately of same width along its length. Odontodes on pectoral-fin spine distributed on lateral border of spine and gradually increasing in size towards tip. Pectoral-fin branched rays becoming progressively shorter posteriorly. Pelvic fin i,5; pelvicfin unbranched ray thick and shorter than branched rays. Odontodes on ventral surface of pelvic-fin unbranched ray pointing mesially. Interradial membrane of pelvic fin fringed distally. Anal-fin i,5; its unbranched ray ticker and slightly shorter than remaining branched rays. First unbranched analfin ray covered with odontodes. Caudal fin I,14,I; emarginate. Total vertebrae 27 (2 cs).

Color in alcohol. Background color of dorsal and lateral portions of head and trunk light brown or yellowish tan, lateroventral and ventral surfaces light yellow to yellowish white ( Fig. 1 ). Dorsal surface of snout with diverging and then somewhat parallel lighter marks, beginning at snout tip, merging anterior to nostrils, and sometimes continuing between nostrils. Posterior portion of head and predorsal region with scattered dark chromatophores concentrated in inconspicuous blotches and leaving lighter areas. Dark brown lateral stripe from side of snout, crossing eye and ending at end of caudal peduncle, clearly delimiting white ventral coloration. Trunk with four conspicuous dark brown bars, extending transversely from dorsal midline to lateral dark stripe. First bar situated at dorsal-fin origin, second bar immediately posterior to dorsal-fin base and ending near end of depressed dorsal-fin rays. Third dark bar widest, on caudal peduncle immediately posterior to anal-fin base. Fourth bar immediately anterior to caudal fin. Ventral surface mostly unpigmented, except for few inconspicuous dark spots lateral to anal-fin origin. Fins mostly hyaline, with few dark spots. Dorsal-fin spine and branched rays with 2-3 dark brown spots. Pectoral-fin spine with 4-5 inconspicuous dark spots, branched rays hyaline or with fewer and inconspicuous spots. Pelvic fin unpigmented. Anal fin mostly unpigmented but with 2-3 inconspicuous dark dots in unbranched ray. Caudal fin with large, elongated or oblique dark-brown to black blotch at base of central rays, continuous with lateral stripe, and two inconspicuous, transverse dark-brown bands. First band inconspicuous, second band conspicuous, in posterior third of fin, but leaving tips of outermost rays unpigmented. Premaxillary and dentary toothcrown light ochre to golden yellow. Tip of odontodes of first unbranched ray of pectoral, pelvic, and anal fins bright orange.

Sexual dimorphism. As typical of the Hypoptopomatinae, males of Curculionichthys hera possess a conical urogenital papilla posterior to vent, which is absent in females, and a fleshy skin flap on the dorsal margin of the unbranched pelvicfin ray, even in juvenile stage. In addition to that, females are significantly larger than males, with body size of the examined sample ranging from 21.8 to 25.7 mm SL, while males examined range from 18.7 to 20.6 mm SL. On the other hand, males show a remarkably secondary sexual dimorphism in the wider naris diameter, 10.5-13.6% HL (vs. 6.6-9.9% HL in females; Fig. 3 ), which is possibly associated with their ability to locate females during the reproductive period.

Distribution. Curculionichthys hera is so far known from the igarapé do Onça and igarapé Moju, two “terra firme” headwater creeks tributaries to the upper rio Curuá-Una, a small river affluent to the Amazon, immediately south of the town of Santarém, Pará State, Brazil, at approximately 60-80 m asl ( Fig. 4 ).

Habitat and ecology. The type-locality is a mid-size creek with medium water current, clear water, bottom composed of small rocks, gravel, sand, and occasionally mud, with moderate to large amounts of aquatic submerged and marginal vegetation, where the specimens were collected ( Fig. 5 ). A second locality where the species was found has a rocky bed and boulders, but also sandy stretches, and banks covered by forest.

Conservation status. The extinction risk of Curculionichthys hera is provisionally assessed as low despite the limited knowledge of its geographic distribution. The species is so far known from two creeks tributary to the rio Curuá-Una basin, but the basin is illexplored and additional collecting efforts will likely reveal a broader distribution. As the species is naturally abundant and specific threats were not detected, C. hera is tentatively categorized as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2017). Additional collecting efforts are worth conducting in the rio Curuá-Una basin in order to better understand the geographic distribution of this species.

Etymology. Specific epithet hera from the Latin hera , meaning mistress of the house, lady, or queen, in allusion to the larger size of the females relative to males. A noun in apposition.

Figures

Fig. 1. Curculionichthys hera, holotype, MCP 52500, female, 25.1 mm SL, igarapé do Onça, tributary to rio Curuá-Una on road BR-163 between Belterra and Rurópolis, Belterra, Pará, Brazil.

Fig. 2. Field Emission Scanning Electron Microscopy (FESEM) of snout tip showing hypertrophied odontodes of species of Curculionichthys. a. C. hera, paratype, MCP 51571; b. C. itaim, MCP 51569; and c. C. insperatus, MCP 47070. Scale bars = 1 mm.

Fig. 3. Snout and sexual dimorphism in size of nares of adults of Curculionichthys hera, MCP 51571, paratypes. a. male; b. female. Scale bars = 1 mm.

Fig. 4. Collecting localities of Curculionichthys hera in the rio Curuá-Una basin, on road BR-163 between Belterra and Rurópolis, Belterra, Pará, Brazil. Star represents type-locality.

Fig. 5. Type-locality of Curculionichthys hera, igarapé do Onça, tributary to rio Curuá-Una on road BR-163 between Belterra and Rurópolis, Belterra, Pará, Brazil.

Tables

Tab. 1. Morphometric and meristic data of Curculionichthys hera based on holotype and 29 paratypes (15 males and 15 females). SD = standard deviation.

	Holotype	Min	Max	Mean	SD
Standard length (mm) Male Female	- - 25.1	18.7 18.7 21.8	25.7 20.6 25.7	22.0 19.7 24.2
Percent of standard length
Head length	38.0	36.8	41.4	38.7	1.2
Predorsal length	46.0	43.6	51.2	47.1	1.7
Postdorsal length	40.7	37.8	44.7	40.3	1.5
Prepectoral length	29.9	27.3	33.1	29.6	1.3
Prepelvic length	45.3	42.0	45.6	43.9	1.0
Preanal length	64.9	60.6	68.4	64.3	2.0
Cleithral width	24.2	21.7	27.6	23.8	1.2
Snout-opercle distance	29.6	28.6	33.9	30.4	1.1
Pectoral-pelvic-fins distance	16.7	12.5	16.8	15.2	1.2
Pelvic-anal-fins distance	22.3	18.6	24.4	21.4	1.5
Dorsal-fin spine length	24.8	21.2	27.7	24.3	1.4
Dorsal-fin base length	13.1	8.3	13.9	11.4	1.2
Pectoral-fin spine length	26.8	24.5	31.1	27.6	1.9
First pelvic-fin unbranched ray length	18.7	17.2	23.5	19.8	1.8
First anal-fin unbranched ray length	17.7	14.5	20.7	17.6	1.5
Caudal-peduncle length	29.1	23.9	29.3	26.9	1.6
Caudal-peduncle depth	8.2	5.5	9.1	7.6	0.9
Caudal-peduncle width	5.5	2.3	7.2	5.1	1.0
Body depth at dorsal-fin origin	14.7	11.3	15.9	14.0	1.1
Body width at dorsal-fin origin	19.5	15.3	22.3	17.5	1.6
Percent of head length
Head depth	42.6	35.5	46.0	41.0	2.6
Head width	56.5	52.2	60.9	56.4	2.6
Snout length	53.6	47.5	56.4	51.7	2.2
Orbital diameter	17.3	11.7	21.4	16.0	2.3
Interorbital distance	33.9	28.4	36.3	33.1	2.0
Internareal width	14.3	7.3	14.6	11.0	1.7
Nares diameter	6.6	6.6	13.6	10.1	2.2
Male	-	10.5	13.6	12.1	0.8
Female	-	6.6	9.9	8.1	1.0
Prenasal length	43.2	34.4	45.8	39.0	2.8
Suborbital depth	15.1	10.3	16.4	13.8	1.5
Barbel length	5.8	2.8	8.5	5.5	1.4
Counts	Holotype	Low	High	Mode
Rigth premaxillary teeth	21	15	22	21
Left premaxillary teeth	20	15	21	20
Rigth dentary teeth	20	14	21	20
Left dentary teeth	19	12	21	19
Plates in median lateral series	23	22	23	23
Plates in mid-dorsal series	8	7	8	8
Predorsal plates	2	2	2	2
Branched pectoral-fin rays	6	5	6	6
Branched dorsal-fin rays	6	6	7	6
Branched pelvic-fin rays	5	5	5	5
Branched anal-fin rays	5	4	5	5
Branched caudal-fin rays	14	14	14	14