Acanthemblemaria hastingsi, Lin, Hsiu-Chin & Galland, Grantly R., 2010

Lin, Hsiu-Chin & Galland, Grantly R., 2010, Molecular analysis of Acanthemblemaria macrospilus (Teleostei: Chaenopsidae) with description of a new species from the Gulf of California, Mexico, Zootaxa 2525, pp. 51-62 : 55-60

Acanthemblemaria hastingsi new species

Cortez Barnacle Blenny ( Fig. 3 )

Acanthemblemaria hancocki macrospilus (in part): Brock 1940

Acanthemblemaria macrospilus (in part): Stephens 1963; Rosenblatt and McCosker 1988; Hastings and Robertson 1998; Hastings 2000 ; Thomson et al. 2000

Acanthemblemaria macrospilus: Lindquist 1985 ; Kotrschal and Lindquist 1986; Lindquist and Kotrschal 1987; Thomson and Gilligan 2002

Acanthemblemaria n sp.: Hastings 2009

Holotype. SIO 65-272, 43.6 mm SL, male, Mexico, Gulf of California, Canal San Jose, 24°60’ N, 110°46’ W, 3 m depth, collected with Chemfish, 8-July-1965.

Paratypes. SIO 65-272, n=50, 22– 46 mm SL, collected with the holotype; SIO 65-342, n=68, 23– 49 mm SL, Mexico, Gulf of California, Isla Santa Cruz, 10 m depth, collected with Chemfish, 22-July-1965; SIO 59- 228, n=106, 14.5–45 mm SL, Mexico, Gulf of California, Isla San Ignacio de Farallon, 5–10 m depth, collected with Rotenone, 1-April-1959; SIO 59-225, n=236, 20– 54 mm SL, Mexico, Gulf of California, Punta Pescadero, 5 m depth, collected with Rotenone, 28-March-1959; USNM 317625, 3, 32–40.2 mm SL, Mexico, Gulf of California, Isla San Pedro Nolasco, 6 m depth, 20-June-1990; LACM 57208-1, n=10, collected with SIO 59-225; FMNH 119163, n=10, collected with SIO 59-225; CAS 229775, n=10, collected with SIO 59-225. Ten specimens from each SIO lot are cleared and stained.

Diagnosis. Acanthemblemaria hastingsi can be distinguished from other Pacific members of this genus excluding its closest relatives, A. macrospilus and A. mangognatha , by combination of a single row of large brown blotches along its lateral midline and pointed (vs. club-like or ridge-like) head spines ( Figs. 3 and 4 ). It can be distinguished from A. macrospilus and A. mangognatha by a dark swath of melanophores on the dorsal fin in both males and females that highlights the bright orange coloration on that fin ( Fig. 3 B); presence of scattered melanophores reaching the tip of the lower jaw; and expression of orange as the primary bright head color. Acanthemblemaria hastingsi is further distinguishable from A. macrospilus by 71 fixed mutations in COI and 20 fixed mutations in the D-loop region of its mitochondrial genome ( Tables 2 and 3).

Description. Variable meristic data summarized in Table 4 . All examined paratypes with 11 precaudal vertebrae; holotype with 12. No variation in pectoral-fin rays (13), primary caudal-fin rays (13), anal-fin spines (2), pelvic-fin spines (1), and pelvic-fin rays (3).

Body long and slender (body depth in standard length nearly 6.5 times, Table 5). Head long (contributing to nearly 20% of standard length, Table 5). One pair of usually unbranched supraorbital cirri; occasionally shallowly branched and rarely deeply branched, never more than once. Nasal cirri on anterior nostrils and always branched, occasionally more than once. No cirri on posterior nostrils. Dorsal fin single, notched – at 24th spine on holotype. Caudal fin truncate. Upper jaw large (about 1.8 times in head, Table 5) and always extending beyond level of posterior edge of orbit and nearly as far back as dorsal-fin origin. Several bones of neurocranium covered with spines ( Fig. 4 ). Frontals with most well developed spine field, forming diamondshaped patch, extending posteriorly from point in interorbital space ( Fig. 4 ).

The following measurements (mm) were taken from the holotype: standard length 43.6; head length 10.9; upper jaw length 6.0; orbital diameter 2.6; snout length 2.2; interorbital width 1.9; predorsal length 7.8; preanal length 19.0; caudal peduncle depth 3.4; body depth at anal-fin origin 6.5. Variation in paratypes summarized in Table 5, along with data for similar species.

Vertebrae Fin Elements

Caudal Total Dorsal Spines D. Soft Rays Dorsal Total Anal Soft Rays TABLE 5. Mean size ratios (SD) of A. hastingsi (sorted by sex), A. macrospilus , and A. mangognatha . Male A. hastingsi standard length range = 33.7–51.0 mm. Female A. hastingsi standard length range = 29.8–40.0 mm. A. macrospilus standard length range = 25.3–41.7 mm. A. mangognatha standard length range = 17.0– 27.4 mm. HL=head length; SL=standard length; JL=jaw length; OD=orbit diameter; BD=body depth; SnL=snout length; PdL=predorsal length; and PaL=preanal length. + indicates a ratio where the values for A. hastingsi males and females are significantly different according to an unpaired t-test.

Cephalic pore counts are as follows, with numbers of representative specimens (total n=44) in parentheses. Mandibular: 4(43*), 5(1); common: 1(44*); preopercular: 5(43*), 6(1); posttemporal: 4(43*), 5(1); lateral supratemporal: 3(4), 4(34*), 5(6); median supratemporal: 1(1), 2(3), 3(39*), 4(1); anterior infraorbital: 3(43*), 4(1); posterior infraorbital: 4(5), 5(29*), 6(9), 7(1); supraorbital: 3(3), 4(36*), 5(5); frontal: 3(7), 4(9*), 5(13), 6(2), 8(1); commissural: 0(3), 1(37*), 2(3); anterofrontal: 1(3), 2(41*); and nasal: 1(44*).

Coloration. Males and females exhibit series of distinct saddles, from nape to posterior end of dorsal fin, due to dense melanophore expression in these areas. Most often, individuals (including the holotype) with eight saddles, but individuals with seven (as a result of melanophore expression between two expected posterior-most saddles) or nine (as a result of an area of no dark coloration dividing posterior saddle) were observed. In some males, dark head and anterior body coloration mask distinction of first or first two saddles. Individuals of both sexes exhibit seven blotches along lateral midline of body, almost always more distinct in females than in males (which are generally darker; only five easily distinguishable in one especially dark male). Anterior blotch hidden by adpressed pectoral fin, with remaining blotches roughly offset from dorsal saddles. Posterior blotch most elongate, stretching to (but not onto) caudal fin, and often contains regions of fewer melanophores, obscuring overall shape. No other dark coloration present on bodies of either males or females. Females with distinct dark blotches on pectoral base and cheek; often masked by dark head coloration in males but occasionally present. Melanophores present to tip of lower jaw in both sexes (more dense in males than in females). In life, primary bright color on head orange, and faint blue spots occasionally located on cheeks and head. No noticeable differences in coloration of individuals fixed in formalin and those preserved in ethanol.

Individuals of both sexes with very dark, distinct swath of melanophores along lower half of anterior, spinous dorsal fin ( Fig. 3 ). In males, this swath begins at base of first dorsal spine and extends posteriorly to fifth-seventh spine ( Fig. 3 A). Some individuals with fewer melanophores at base of first or first two spines than in remainder of swath, but always with some. In females, base of first or first two dorsal-fin spines usually free of melanophores, creating a triangular patch of no color and causing swath to be more j-shaped. In life, primary bright color on dorsal fin orange, windowed by melanophore swath described above and by a fainter band of melanophores along top edge of fin ( Fig. 3 B). Scattered melanophores present along remainder of spinous dorsal fin. Anal fin characterized by one broad band of melanophores running full length of fin in both males and females (significantly less dense than in dorsal swath; Fig. 3 A). Caudal fin, pelvic fins, and pectoral fins with very few, scattered melanophores; otherwise colorless.

Sexual dimorphism. In addition to differences in coloration discussed above, the sexes are distinguishable by shape of genital papilla; pointed and simple in males and broader and fimbriate in females ( Böhlke 1957). Males and females also differ slightly in body shape (Table 5). Orbital diameter consistently fits fewer times into snout length of females than males (P<0.0001, unpaired t-test), and orbital diameter fits fewer times in head length in females than in males (P<0.0001). Females seem more slender, with body depth fitting in standard length more times than in males (P<0.001). No noticeable differences in head pore pattern and count or in meristics.

Distribution. Acanthemblemaria hastingsi is limited to the GOC where it is known to occur from Mulegé to Cabo San Lucas along the Baja Peninsula and between Isla San Pedro Nolasco and Isla San Ignacio de Farallon along the Mexican continental mainland ( Hastings & Robertson 1998). Gulf species in this genus are known to exhibit depth partitioning, and A. hastingsi is typically found 0–13 m deep ( Lindquist 1985).

Etymology. Acanthemblemaria hastingsi is named for Philip A. Hastings who has contributed to our knowledge of chaenopsid blennies for more than 25 years.

Remarks. We provide molecular and morphological evidence that the formerly recognized color morphs of A. macrospilus are distinct species. This observation of closely related species living on either side of, and separated by, the Sinaloan Gap is not unique and occurs in at least three other pairs of chaenopsid tube blennies ( Hastings 2000 ). The identification of two mitochondrial lineages with unique haplotypes ( Fig. 2 ) and abundant fixed mutations ( Tables 2 and 3) adheres to the definition of unique evolutionary histories in the Phylogenetic Species Concept ( Mishler & Theriot 2000). In addition, the COI divergence value of 15.50% is much higher than that in previously studied congeneric Australian fish species pairs (of 9.9%; Ward et al. 2005) further suggesting the existence of two species. In addition to mitochondrial evidence, we also attempted to find independent genetic support from nuclear DNA. Based on nuclear intron marker S7-1 data, differentiation between the two mitochondrially diagnosable species is supported by the significant fixation index, but no genealogical pattern was observed. Even though nuclear intron markers are thought to be highly variable and commonly applied for resolving relationships among terminal taxa, it is not unusual to have much less informative mutations and therefore less resolution compared to mitochondrial DNA, as we show here (e.g., Creer et al. 2003; Lozier et al. 2008; Von Der Heyden et al. 2008).

Rosenblatt and McCosker (1988) presented a morphological key to the Pacific species of Acanthemblemaria that were known at that time of publication. Using their publication, individuals of A. hastingsi , as well as individuals of the closely related and morphologically similar A. macrospilus and A. mangognatha , all key out to A. macrospilus . Head and dorsal-fin coloration constitute the best morphological character to discern individuals of these three species. Unlike in A. hastingsi , the melanophores on the lower jaws of individuals of A. macrospilus do not reach all the way to the distal end. Furthermore, the primary bright head color in A. macrospilus is red (vs. orange in A. hastingsi ). The dorsal fin melanophore patterns help to distinguish individuals of A. hastingsi from A. macrospilus and A. mangognatha . Individuals of A. macrospilus almost never have melanophores reaching the base of the first dorsal fin and more typically have a dark, round spot or stretched out spot instead of a swath. Also, the primary bright color on the dorsal is red (vs. orange in A. hastingsi ), and the windowing effect around that color is not present or is less distinct. Individuals of A. mangognatha have more broadly scattered, less dense melanophores throughout the anterior dorsal fin that do not form as distinct of a swath or spot and do not create a windowed patch of color. Finally, individuals of A. mangognatha attain a smaller body size than individuals of both A. hastingsi and A. macrospilus (Table 5).

Materials examined. Acanthemblemaria macrospilus : SIO H46-245-A, n=4, Mexico, Guerrero, near Acapulco, 15-September-1946; UAZ 70-22-8, n=5, Mexico, Oaxaca, Puerto Escondido, 8-June-1970; UAZ 71-61-2, n=34, Mexico, Jalisco, Bahia Banderas, Puerto Vallarta, Los Arcos Rocks, 26-July-1971; UAZ 77- 41, n=71, Mexico, Punta Santiago, near Manzanillo, 30-June-1977. Acanthemblemaria mangognatha : SIO 97-216, n=12, Mexico, Islas Revillagigedos, Isla Socorro, 29-October-1990.

Figures

FIGURE 2. Bayesian inference phylogeny based on 560 bp COI, 422 bp D-loop and the combined data with A. hancocki as the outgroup. Numbers above the nodes are posterior probabilities above 50.

FIGURE 3. (A) Acanthemblemaria hastingsi, holotype (SIO 65 - 272), 43.6 mm SL. (B) Acanthemblemaria hastingsi, life colors.

FIGURE 4. Scanning electron microscope image of Acanthemblemaria hastingsi head spination (SIO 65 - 318; from Rosenblatt and McCosker 1988, fig 2 c).

Tables

TABLE 4. Frequency distribution of vertebral numbers and median fin elements of A. hastingsi, A. macrospilus, and A. mangognatha. Acanthemblemaria hastingsi data sorted by paratype collection site (first four rows). Acanthemblemaria macrospilus and A. mangognatha data from Stephens et al. (1966) Table 2. * marks the data that includes the A. hastingsi type specimen.

	31 32*	33	42	43	44*	23	24*	25	12	13*	14	35	36	37*	38	23	24	25	26*
SIO 65-272 (n=10)	0 7	3	0	7	3	0	4	6	2	6	2	0	0	4	6	0	0	3	7
SIO 59-228 (n=10)	3 6	1	3	6	1	1	5	4	2	7	1	1	0	5	4	0	0	6	4
SIO 59-225 (n=10)	0 7	3	0	7	3	0	7	3	0	6	4	0	0	3	7	0	0	5	5
SIO 65-342 (n=10)	1 8	1	1	8	1	0	5	5	3	7	0	0	0	8	2	0	1	8	1
A. macrospilus (n=30)	n/a					3	25	2	3	26	1	0	5	23	2	1	11	16	2
A. mangognatha (n=9)	n/a					1	8	0	1	7	1	0	2	6	1	0	0	8	1