Rhinotocinclus bockmanni (Carvalho & Datovo, 2012), 2022

Reis, Roberto E. & Lehmann A., Pablo, 2022, A new genus of armored catfish (Siluriformes: Loricariidae) from the Greater Amazon, with a review of the species and description of five new species, Neotropical Ichthyology (e 220002) 20 (2), pp. 1-100 : 63-65

Rhinotocinclus bockmanni (Carvalho & Datovo, 2012) , new combination

( Fig. 35 ; Tab. 7 )

Hisonotus bockmanni Carvalho & Datovo, 2012:266 (Type-locality: Brazil, Pará State, Jacareacanga Municipality, sandbank at Rio Cururu, tributary to Rio Teles Pires, tributary to Rio Tapajós, 08°53’42.2”S 57°14’27.8”W, 140 m asl. Holotype: LIRP 8139).

Diagnosis. Rhinotocinclus bockmanni is distinguished from all congeners, except for R. dani , R. hera , R. pentakelis , R. marginalis n. sp., and R. loxochelis n. sp. by having the dominant color pattern formed by dark bars on body well separated and distinct (Fig. 7D; vs. dominant color pattern formed by wide dark bars partially coalesced or closed together, or formed by a dark stripe from the snout tip, through the eye and extending to end of caudal peduncle); having two separate light lines from snout tip diverging to each nostril (Fig. 6E, F; vs. light lines on snout absent, Y- or V-shaped); and by having teeth with yellow cusps (Fig. 5C; vs. cusps brown or light ochre). Rhinotocinclus bockmanni is further distinguished from R. britskii , R. kwarup , R. eppleyi , R. longirostris , R. polyochrus , R. variola , R. yaka , R. discolor , R. isabelae , and R. pilosus by lacking an adipose fin (vs. adipose fin present). Rhinotocinclus bockmanni is further distinguished from congeners, except R. dani , R. pentakelis , R. marginalis n. sp., and R. loxochelis n. sp., by having small platelets at adipose-fin position (vs. small platelets absent). Rhinotocinclus bockmanni is distinguished from R. dani , R. hera , R. pentakelis , R. marginalis n. sp., and R. loxochelis n. sp. by having a triangular dark spot at the dorsal-fin membrane (vs. dorsalfin dark spot absent), and by lacking or having a very inconspicuous dark bar 2 on body (vs. bar 2 present and conspicuous).

Geographical distribution. Rhinotocinclus bockmanni occurs in the lower and middle rio Tapajós basin, including the rio Teles Pires in the state of Pará, Brazil ( Fig. 36 ).

Remarks. Rhinotocinclus bockmanni was originally described and so far known from the rio Cururu, tributary to rio Teles Pires near Jacareacanga, Pará. We herein record this species to the lower Tapajós downstream from the mouth of rio Jamanxim, extending the distribution o the north by ca. 500 km in straight line. Rhinotocinclus bockmanni , listed as Hisonotus bockmanni , is currently assessed as Data Deficient (DD) in the Brazilian regional assessment by ICMBio (2018). Based on the new record this species should be reassessed.

Material examined. Rio Tapajós basin, Pará State, Brazil: LIRP 8139 , holotype, LIRP 8140 , 2 of 3 + 1 cs paratypes (2 measured), MCP 46046 , 3 paratypes (3 measured), sand bank of rio Cururu, tributary to rio Teles Pires , rio Tapajós basin, Jacareacanga, 08°53’42.2”S 57°14’27.8”W . INPA 6924 , 3 (3 measured), rio Tapajós at Pimental, below mouth of rio Jamanxin , Itaituba, 04°33’41”S 56°15’50”W.

Figures

FIGURE 35 | Rhinotocinclus bockmanni, paratype, MCP 46046, 23.0 m SL, female, sand bank of rio Cururu, tributary to rio Teles Pires, rio Tapajós basin, Jacareacanga, Pará, Brazil.

FIGURE 36 | Geographic distribution of Rhinotocinclus species of the R. bockmanni group in southeastern Amazon basin. Rhinotocinclus bockmanni (black dots); R. dani (red dots); R. hera (pink dots); R. loxochelis n. sp. (blue dots); R. marginalis n. sp. (white dots); R. pentakelis (yellow dots). T = Type-locality.

Tables

TABLE 7 | Descriptive morphometrics of Rhinotocinclus species. Values given as percent of standard length or head length. Range includes the holotype (Hol), SD = standard deviation.

	R. bockmanni n = 8					R. dani n = 14					R. hera n = 10
Character
	Low	High	Mean	SD	Hol	Low	High	Mean	SD	Hol	Low	High	Mean	SD
Standard length (mm)	18.3	23.0	19.8		27.4	20.4	27.4	24.1		25.2	19.4	26.1	22.6
Percent of SL
Body depth	17.2	22.2	20.0	1.89	17.3	16.3	18.3	17.1	0.58	15.8	14.6	17.5	16.0	0.93
Predosal distance	47.5	51.2	49.3	1.21	48.6	47.5	49.8	48.4	0.77	49.0	47.2	50.5	48.6	0.92
Prepelvic distance	44.4	47.3	45.9	1.08	45.3	43.7	45.7	44.8	0.56	44.4	43.3	47.4	44.7	1.53
Preanal distance	64.7	67.6	66.0	0.92	65.1	63.8	66.1	65.1	0.69	64.8	63.4	67.0	64.4	1.13
Preadipose distance	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Dorsal-fin spine length	24.2	28.3	26.1	1.56	24.0	24.0	27.0	25.3	0.90	25.1	21.5	25.1	23.7	1.13
Anal-fin unbranched ray length	18.2	21.3	19.0	1.09	15.5	15.5	19.3	16.6	1.07	18.3	14.4	18.3	16.7	1.30
Adipose-fin spine length	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Pectoral-fin spine length	29.3	31.6	30.3	0.74	29.8	29.2	31.8	30.4	0.82	29.8	27.6	29.9	28.9	0.88
Caudal peduncle depth	10.6	11.6	11.1	0.37	8.8	8.8	9.9	9.3	0.28	8.3	7.8	9.3	8.6	0.50
Dorsal-adipose fin distance	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Dorsal-fin base length	11.8	14.3	13.1	0.75	11.3	9.8	12.7	11.5	0.87	9.3	9.3	12.3	10.3	1.08
Lower caudal-fin principal ray	28.4	34.1	31.0	1.96	-	24.3	27.9	26.4	1.12	25.3	24.3	29.7	26.7	1.93
Cleithral width	24.2	26.7	25.4	0.91	23.6	23.6	26.5	25.3	0.91	24.5	23.6	26.0	24.6	0.72
Head length	38.4	41.6	39.9	0.98	38.3	36.3	40.0	38.2	1.1	37.6	35.1	41.2	38.5	1.95
Percent of HL
Head depth	41.3	45.4	43.0	1.57	42.9	39.9	43.5	42.4	0.9	42.8	39.9	45.5	42.2	1.97
Interorbital distance	32.7	36.1	34.4	1.23	39.2	36.2	41.9	38.7	1.6	36.4	33.7	37.7	35.4	1.37
Orbital horizontal diameter	16.2	18.6	17.5	0.86	14.6	13.6	16.7	15.3	0.8	16.6	15.1	17.3	16.5	0.68
Snout length	49.0	52.2	50.3	1.07	53.1	50.8	55.6	52.7	1.2	52.8	51.9	55.6	53.5	1.40
Internarial distance	6.6	10.7	8.6	1.26	11.0	9.6	12.0	11.0	0.7	9.8	7.2	11.2	9.9	1.22
Tooth count
Premaxilla	11	14	12.5	0.93	26	19	28	21.9	2.7	20	16	22	18.7	2.26
Dentary	9	12	11.0	1.07	22	16	22	19.4	1.7	21	15	21	17.4	2.01