Roa rumsfeldi, Rocha, Luiz A., Pinheiro, Hudson T., Wandell, Matt, Rocha, Claudia R. & Shepherd, Bart, 2017

Rocha, Luiz A., Pinheiro, Hudson T., Wandell, Matt, Rocha, Claudia R. & Shepherd, Bart, 2017, Roarumsfeldi, a new butterflyfish (Teleostei, Chaetodontidae) from mesophotic coral ecosystems of the Philippines, ZooKeys 709, pp. 127-134 : 128-130

Roa rumsfeldi sp. n. Figure 1, 2, Table 1 Deep-blackfin butterflyfish

Type locality.

Puerto Galera, Philippines.

Holotype.

PNM 15198 (Field number: HTP 506). 77.53 mm SL, GenBank accession number MF995631, Puerto Galera, Oriental Mindoro, Philippines. 13°31'17.68"N, 120°59'41.78"E, depth 110 m, collected by LA Rocha using a Hawaiian sling, 10 April 2015 (Figure 1).

Comparative material.

Roa modesta CAS 238385, CAS 27415, CAS 15627, CAS 15897; R. jayakari CAS 73228 (as Chaetodon jayakari ). Data from R. australis , R. excelsa and R. modesta also from Kuiter (2004).

Diagnosis.

Roa rumsfeldi sp. n. differs from all of its congeners by the smaller number of pored scales in the lateral line pored scales (27 versus 37-46 in other Roa ), longer snout (35.9% in HL vs. 28.2-35.5%), shorter first dorsal ray (12% in SL vs. 16.6-26.6%), longer caudal peduncle (8.5% in SL vs. 4.2-8.2%), shorter caudal fin (15.9% in SL vs. 19.8-25.9%), and a dark brown pelvic-fin spine (white in all other known Roa species).

Description.

Dorsal fin rays XI, 20, last soft ray branched to the base and counted as one; dorsal-fin base length: spines 40.0% in SL, and soft rays 31.1% in SL; spines increase in height from the first to the fourth: length of first spine 9.1% in SL, length of second spine 18.3% in SL, length of third spine 24.5% in SL, length of fourth spine 29.1% in SL. Soft dorsal fin follows sharp descent of rear portion of body. First soft ray 12.0% in SL. Anal-fin rays III, 17, last soft ray branched to the base and counted as one; anal-fin base 34.2% in SL; second spine very long, 25.3% in SL. Pectoral fin 13; length 29.1% in SL (Table 1). Pored lateral-line scales 27, plus 13 scales (without pores) to the peduncle. Body deep, 69.8% in SL, and compressed, 15.5% in SL; large head, length 41.1% in SL; snout long, length 35.9% in HL; eye diameter 32.2% in HL; interorbital 27.5% in HL; caudal peduncle depth 10.7% in SL, and length 8.5% in SL (Table 1).

Origin of dorsal fin above the origin of pectoral fin, posterior end of head; fin base long and mostly horizontal; soft part of dorsal fin curves downward from the third ray to caudal peduncle; soft rays posterior margin vertical; origin of anal fin below 9th spine of dorsal fin; pelvic fin with strong spine and filamentous first soft ray.

Body and head with ctenoid scales, becoming smaller towards nape and snout. Scales extending to about one third of the median fins. Tubed scales of lateral line rising at a steep angle from origin with 22 scales in an almost straight line, bending abruptly downward, ending behind posterior third of soft dorsal fin.

Color in life.

Roa rumsfeldi sp. n. (Figure 1, 2) is white with three vertical dark brown bands. The first band is the narrower and runs from the origin of the dorsal fin through eye and over cheek; the second partially covers 2nd to 7th dorsal spines, going down towards the abdomen; and 3rd from the last 3-4 dorsal spines towards caudal peduncle, narrowing and covering the end of anal fin rays. Two black spots with white borders, one on the 2nd dorsal fin spine and the other on the soft dorsal fin between 2nd and 7-8th rays; all anal fin spines are white; pelvic fin, including spine, dark brown; caudal fin brown basally with translucent rays.

Color in alcohol.

As described above in color in life, but with lighter brown bands.

Etymology.

We name Roa rumsfeldi to honor Donald Rumsfeld who immortalized the quote: "there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don’t know we don’t know." He said that when referring to the uncertainties of war, but we think it applies perfectly to the taxonomy of MCE species: We only realized this species was new after we took a good look at it here at the aquarium in San Francisco, so we think it’s a perfect example of an unknown unknown.

Distribution and habitat.

Roa rumsfeldi sp. n. is only known to occur in the Verde Island Passage, central Philippines. It was found on MCEs of Puerto Galera, Oriental Mindoro, and Bauan, Batangas, between 100 and 130 m depth. However, the species likely has a wider distribution and remains undetected because of its preferred depth range. The ecosystems where it was found vary from sheltered rocky outcroppings heavily covered by fine sediment to areas exposed to strong currents. The ambient seawater temperature varied between 19 and 21°C during our dives, which were conducted in April-May over several years. Azooxanthellate gorgonians, black corals, and solitary stony corals are the most abundant benthic invertebrates in this habitat.

Comparative remarks.

In addition to the singular characteristics presented in the diagnosis section, Roa rumsfeldi sp. n. differs from its congeners by a lower number of dorsal soft rays (20) than R. jayakari (22-24); longer head (41.0% in SL) than R. excelsa (34.9-37.1); fewer dorsal-fin rays (20) and shorter dorsal-fin rays base (31.1% in SL) than R. modesta (22 rays and 35.3-40.8% in SL); and shorter 3rd anal-fin spine (12.8% in SL) and longest anal-fin ray (13.8% in SL) than R. australis (17.6-23.9, 18.9 -23.0 and 17.5-23.2% in SL, respectively). Moreover, the COI gene sequence of Roa rumsfeldi does not match any other Roa species available at Genbank. The uncorrected genetic divergence at the COI gene between R. rumsfeldi and the two other available Roa ( R. jayakari and R. modesta ) is 10.5% and 8.4%, respectively.