Chriolepis prolata, Hastings, Philip A. & Findley, Lloyd T., 2015

Hastings, Philip A. & Findley, Lloyd T., 2015, Chriolepis prolata, a new species of Atlantic goby (Teleostei: Gobiidae) from the North American continental shelf, Zootaxa 3904 (4), pp. 589-595 : 590-595

Chriolepis prolata sp. nov.

“Platform Goby”

( Figs. 1–3 )

Dormitator (?) sp. Adams & Kendall 1891

Chriolepis bilix (in part, USNM 43554) Hastings & Findley 2013

Holotype. USNM 230001 (formerly USA 05362), male, 23.0 mm SL, northeastern Gulf of Mexico, ca 127 km south of St. George's Island, Franklin County, Florida, 28° 24.4’N, 84° 55.2’W, 29 October 1977, 91m depth.

Paratypes. AMNH 87272 (formerly USA-SAM 775-08), female, 20.1 mm SL, northeastern Gulf of Mexico, ca 37 km south of Navarre Beach, Santa Rosa Island, Florida, 30° 08’N, 86° 45’W, 29 July 1975, ca 110m depth; SIO 14–37, female, 26.4 mm SL, northeastern Gulf of Mexico, ca 123 km east of Sanibel Island, Florida, 26° 16.8’N, 83° 23.8’W, 4 May 1981, 56m depth; SIO 14–38, male, 24.5 mm SL, northeastern Gulf of Mexico, ca 161 km east of Sanibel Island, Florida, 26° 16.72’N, 83° 46.82’W, 4 November 1980, 78m depth; SIO 14–39, female, 16.8 mm SL, western Atlantic Ocean, ca 104 km east of James Island, South Carolina, 32° 29.3’N, 78° 48.4’W, 24 September 1978, ca 54–56m depth.

Additional material. USNM 43554, sex unknown, 25.4 mm SL, Gulf of Mexico, off Cape Sable, southwestern Florida, 25° 02’N, 83° 34’W, 17 or 18 February 1889, 68m depth. Formerly assigned to Chriolepis bilix (see Comparisons, below).

Diagnosis. A species of Chriolepis with 11 or 12 second dorsal-fin elements, 11 or 12 anal-fin elements and 17 to 19 pectoral-fin rays. Body extensively scaled: mid-lateral scales extending from just behind pectoral-fin axil to caudal-fin base in approximately 34–37 rows. Most scales weakly ctenoid, extending anteriorly in a wedge to level of first dorsal-fin insertion or slightly posterior to pectoral-fin axil. Anteriormost lateral scales cycloid (lacking ctenii), in two to seven midlateral rows and extending anteriorly to near pectoral-fin axil and posteriorly along bases of second dorsal fin and anal fin. Scales absent on belly and isthmus. Fifth (innermost) pelvic-fin ray well developed, slightly longer than second pelvic-fin ray to longer than all other pelvic-fin rays. Enlarged recurved canines present in medial tooth row of lower jaw. First two anal-fin pterygiophores inserted anterior to first haemal spine.

Description. Vertebrae 27: 11 precaudal + 16 caudal ( Fig. 2 ). First dorsal fin with seven spines; first through fifth spines closely spaced, sixth and seventh more widely spaced. Dorsal-fin formula 3- 221110. No dorsal-fin spines elongate; first three spines when adpressed extend posteriorly to insertion of second fin-ray element of second dorsal fin. Second dorsal fin separated from the first by a distance equal to approximately one-half eye diameter. Second dorsal fin with a thin flexible spine followed by 10–11 segmented rays (11–12 total elements); last ray branched from its base. Anal fin with a thin flexible spine and 10–11 segmented rays (11–12 total elements); last ray single or branched from its base. First two anal-fin pterygiophores inserted anterior to first haemal spine ( Fig. 2 ). Caudal fin truncate, with eight upper and eight lower segmented rays and six upper and five lower procurrent rays (12 central rays branched in holotype). Pectoral fin angulate (central rays longest) with 17–19 rays; longest pectoral-fin ray when adpressed extends to level of anal-fin origin. Pelvic fin with a thin flexible spine and five rays, inserted slightly posterior to level of pectoral-fin base. Pelvic fins separate with no interspinal frenum and no membrane connecting innermost rays of left and right fins, although a low ridge present medially between fins. First through fourth pelvic-fin rays branched with slightly flattened distal tips; fifth ray well-developed (not splintered to fourth), unbranched, comparatively thin, and not flattened distally. Fourth pelvicfin ray longest ray in that fin in four of five type specimens (including holotype), reaching posterior rim of anus when adpressed. Fifth pelvic-fin ray longest in SIO 14–38, extending well-past anus when adpressed.

Head slightly wider than deep, cheeks not inflated. Eyes large (horizontal diameter approximately one-third head length), superior, with fleshy orbital margins. Interorbit narrow, eyes closely approximated dorsally. Lower jaw inclined upward at approximately 40-degree angle to horizontal body axis and projecting anteriorly just beyond tip of upper jaw. Posterior margin of upper jaw extends to a vertical through anterior margin of pupil. Nostrils in short tubes; anterior tube length approximately equal to two-thirds pupil diameter; posterior tube length equal to approximately one-half length of anterior tube length (holotype). Urogenital papilla conical in males (including holotype), rounded in females.

Cephalic sensory pores absent. Sensory papillae (superficial or free neuromasts, “epipores”) as in Figure 3 . Body extensively scaled for a Chriolepis ( Fig. 3 ); scales deciduous with many missing in available specimens. Laterally, scales extend from just behind pectoral-fin axil to caudal-fin base in approximately 34–37 irregular rows. Most scales bearing small ctenii along posterior scale margins; scales decrease in size, and associated ctenii decrease in size and number anteriorly; anteriormost two (SIO 14–37) to approximately seven (holotype) rows of scales cycloid, lacking ctenii. Cycloid scales also present along sides of abdomen and posteriorly along bases of second dorsal fin and anal fin. Head, nape, anterior pectoral-fin base, belly, and isthmus naked ( Fig. 3 ). Modified basicaudal scales present on upper and lower caudal fin, each with 12–15 ctenii.

Upper jaw with an outer row of relatively large, slightly recurved canine teeth, approximately 10–11 per side (none greatly enlarged); teeth widely spaced anteriorly but more closely spaced postero-laterally. A patch of low, close-set teeth medial to outer row, three or four teeth wide anteriorly, tapering to two or three teeth wide posterolaterally. No teeth in medial patch enlarged. Lower jaw with an outer row of four or five canine teeth anteriorly. Medial tooth patch four teeth wide anteriorly, tapering to two teeth wide postero-laterally; most medial teeth small except for six enlarged, recurved canines laterally on each side. No teeth present on vomer and palatines. Tongue tip slightly indented to truncate. Pseudobranchiae in six tufts (holotype). Gill rakers short; first gill arch of holotype with three rakers on upper limb, and eight rakers on lower limb (11 total rakers).

Measurements of holotype in mm: standard length 23.0; predorsal length 8.0; head length 6.6; eye diameter 2.2; snout length 1.2; interorbital width 0.3; upper jaw length 2.5; body depth 3.6; pectoral-fin length 6.5; fourth pelvic-fin ray length 6.0; fifth pelvic-fin ray length 4.3; caudal peduncle depth 2.5.

Life colors unknown. Color of holotype (male, in 45% isopropyl alcohol) faded yellow with head and body densely peppered with fine melanophores. Four ill-defined rectangular blotches present along lateral midline: first under anterior part of first dorsal fin, second under anterior part of second dorsal fin, third under middle of second dorsal fin, and fourth on caudal peduncle. An elongate dash present posteriorly on caudal peduncle, and a similar dash on central caudal fin. Irregular, ill-defined saddles present on dorsum, those between the lateral blotches most distinct. Predorsal area with four irregular saddles and many scattered melanophores. Few melanophores below lateral midline of body. Cheek, snout, suborbital region, lower jaw, pectoral-fin base and isthmus peppered with fine melanophores. Membrane between fourth and fifth branchiostegals with a dense patch of melanophores. Base of genital papilla (male holotype) ringed with melanophores. Belly lacking pigment except for a few scattered melanophores just anterior to anus. First dorsal fin with scattered melanophores, concentrated in an ill-defined blotch between first and second spines. Second dorsal fin with scattered melanophores in six ill-defined lines. Distal three-fourths of anal fin densely peppered with melanophores, its proximal one-fourth with fewer melanophores. Caudal fin with scattered melanophores. Pectoral fin with a few tiny melanophores. Upper portion of outer pectoral-fin base with a small blotch. Pelvic fin with dense melanophores.

Coloration of all paratypes faded at this time. Notes taken by one of us (LTF) approximately six months after capture and preservation of AMNH 87272 (female, in alcohol; specimen provided by C.E. Dawson) include the following. Body with six or seven wide irregular, transverse dark brown bars on a yellowish background; bars broken just above lateral midline and appear dorsally as three or four irregular saddles which extend onto dorsal fins as dark diagonal lines. Lateral midline with seven irregular spots, first five rounded, last two elongated and dash-like; a T-shaped mark at caudal-fin base. Sides below lateral midline peppered with minute melanophores. Top of head with two large, dark “saddles” more or less broken into three or four spots (approximately equal in size to pupil diameter) above cheek and operculum. Isthmus peppered with fine melanophores concentrated in a diffuse dark streak on lower branchiostegal membranes. Pelvic fins dusky, pectoral fins clear. Outer pectoral-fin base with a large, elongate dark spot (left side) or two interconnecting spots (right side), and a spot on axillary side of upper pectoral-fin base. Caudal fin with about three transverse dark bars, most notable as spots on fin rays. Anal fin dark, membranes with large melanophores.

Distribution. Known from the continental shelf (platform) of the northeastern Gulf of Mexico and the western Atlantic Ocean off South Carolina ( Fig. 4 ) from depths of ca 54 to 110 meters.

Etymology. From prolatus (Latin for elongated) in reference to the relatively elongate innermost or fifth pelvic-fin ray compared to that of other known species in the genus.

Comparisons. Chriolepis prolata differs from all other known western Atlantic species of Chriolepis in having a relatively long fifth pelvic-fin ray which may be the longest ray in that fin. It is most similar to Chriolepis bilix Hastings and Findley, 2013 . Both species are unique among known western Atlantic Chriolepis species in having the first two (rather than one) anal-fin pterygiophores inserted anterior to the first haemal spine, and both species have scales essentially covering the entire lateral aspect of the body. In C. bilix , all lateral scales, other than the anteriormost row, are ctenoid, while in C. prolata the anteriormost two to seven rows are cycloid. The development of ctenii on the lateral scales of C. prolata may be size related because they are most extensive in the largest available specimen (SIO 14–37). The belly is scaled in C. bilix but naked in C. prolata . These species also differ in the configuration of the first dorsal fin: the anteriormost two spines are greatly prolonged in C. bilix but no spines are prolonged in C. prolata . Finally, C. prolata has well-developed canine teeth in the lower jaw that are not present in C. bilix .

Chriolepis prolata is known from specimens from the northeastern Gulf of Mexico and the western Atlantic Ocean off South Carolina. One of the so-designated paratypes (USNM 43554) of the recently described Threadspined Goby, Chriolepis bilix Hastings & Findley, 2013 was captured near collecting localities for C. prolata off southwestern Florida ( Fig. 4 ). That specimen, collected in 1889 ( Adams & Kendall 1891), is in extremely poor condition (badly damaged and as brittle as a potato chip) such that the features distinguishing C. bilix and C. prolata are no longer evident (e.g., its pelvic and dorsal fins are broken and many lateral scales are missing). Given its collection from the same general area (ca 140 km south of SIO 14–37 and SIO 14–38) and depth as specimens of C. prolata , and lacking additional critical information on its species identity, we here consider it to represent a specimen of C. prolata , not C. bilix . Due to its extremely poor condition, it is not designated as a paratype of C. prolata . The specific re-allocation of this specimen dictates that the geographical distribution of C. bilix (so far as known) does not include the shelf waters of North America as indicated by Hastings & Findley (2013).

Like C. bilix , C. prolata differs from morphologically similar gobies ( Chriolepis and Varicus ) in the western Atlantic ( Table 1) in having the first two (rather than only the first) anal-fin pterygiophores inserted anterior to the first haemal spine. It resembles Chriolepis vespa Hastings & Bortone, 1981 , and C. benthonis Ginsburg, 1953 , in having a robust body, plump head and relatively large eyes, but differs in having scales essentially covering the entire lateral aspect of the body rather than only the posterior half of the body. It also differs from those two species in total number of elements in the second dorsal fin (11–12 in C. prolata , 10 in C. vespa , and 9 in C. benthonis ) and in the anal fin (11–12 in C. prolata , 7–9 in C. vespa , and 8 in C. benthonis ). Chriolepis fisheri , also from the western Atlantic, differs from all other Atlantic species of Chriolepis in having a notably smaller body, a relatively flat head, and in the absence of scales on the lateral aspect of the body (two specialized basicaudal scales are ___________________________________________________________________________________________________________________

Species D2 A P1 Pelvic Fifth pelvic- AFP Lateral Origin of Belly

fin rays fin ray length scale rows lateral scales

___________________________________________________________________________________________________________________

Chriolepis benthonis 9 8 16 branched <pelvic spine 1 12 D2, ray 6 naked

Chriolepis bilix 12 11-12 19-20 branched> pelvic spine 2 30-35 pectoral axil scaled

Chriolepis fisheri 11-12 10 17-18 branched <pelvic spine 1* absent absent naked

Chriolepis prolata 11- 12 11-12 17-19 branched >>pelvic spine 2 34-37 pectoral axil naked

Chriolepis vespa 10 7-9 15-17 branched <pelvic spine 1 9-14 D2, ray 6-9 naked

Varicus bucca 9-10 8 16 -19 unbranched <pelvic spine 1* 27 pectoral axil naked/scaled

Varicus imswe 8 8 14 -15 unbranched <pelvic spine? 24 D2, ray 1 scaled

Varicus marylinae 9 8 16 -18 unbranched <pelvic spine 1* 18-19 mid-pectoral fin naked

____________________________________________________________________________________________________________________ present in C. fisheri ). Chriolepis prolata differs from morphologically similar gobies in the genus Varicus in having branched pelvic-fin rays (unbranched in Varicus ), the fifth pelvic-fin ray considerably longer than the pelvic-fin spine (shorter than the spine in Varicus ), and greater numbers of second dorsal-fin and anal-fin elements ( Table 1).

Both C. prolata and C. bilix resemble the eastern Pacific species Chriolepis atrimelum Bussing, 1997 , known from a single specimen collected at a depth of 137–146 m at Isla del Coco off Costa Rica ( Bussing 1997). All three species have a fully scaled body and the first two anal-fin pterygiophores inserted anterior to the first haemal spine, but unlike the other two species, C. prolata lacks prolonged dorsal-fin spines.

The presence of the first two anal-fin pterygiophores inserted anterior to the first haemal spine in C. prolata and C. bilix appears to be unique among western Atlantic species of Chriolepis , as well as the related genus Varicus ; all other known western Atlantic species of these genera have only the first anal-fin pterygiophore inserted anterior to the first haemal spine ( Table 1; Birdsong et al. 1988). This feature is shared with C. atrimelum , as well as some other eastern Pacific species of Chriolepis ( Birdsong et al. 1988) . Thus, the importance of this character in determining relationships among the species of these poorly known gobies remains unclear.

Figures

FIGURE 1. Holotype of Chriolepis prolata (USNM 230001).

FIGURE 2. Radiograph of holotype of Chriolepis prolata (USNM 230001).

FIGURE 3. Outline drawing of holotype of Chriolepis prolata (USNM 230001) showing sensory papillae pattern (composite from both sides) and extent of lateral squamation. Right and left cross-hatchings indicate extent of ctenoid and cycloid scales, respectively. Pectoral fin is cut-away (only its base is indicated), and outlines of other fins, shown as dashed lines, are approximate.

FIGURE 4. Distribution map for Chriolepis prolata (circles). The holotype is USNM 230001 and paratypes are AMNH 87272, SIO 14 – 37, SIO 14 – 38, and SIO 14 – 39. The collecting locality for formerly designated paratype of Chriolepis bilix (Hastings & Findley 2013) from off SW Florida (USNM 43554) and the type locality for C. bilix (diamond) in the northern Bahamas (USNM 199058) are also indicated. Map courtesy of GoogleEarth.