Callogobius williamsi, Delventhal & Mooi, 2023

Delventhal, Naomi R. & Mooi, Randall D., 2023, Callogobius williamsi, a new species of goby (Teleostei: Gobiidae) from the Marquesas Islands, with notes on the status of all nominal Callogobius species, Zootaxa 5339 (5), pp. 449-464 : 450-455

Callogobius williamsi sp. nov.

( Figs. 1–9 , Table 1 )

urn:lsid:zoobank.org:act:7C1CACFC-A778-45A7-94E6-18CF77195103

Holotype. USNM 409430 , female, 32.9 mm SL, Marquesas, Fatu Hiva, Mahitoa point, on southwest side of island, on outer rock wall sloping to a flat rubble shelf at about 27 m, 10°32′04″ S, 138°40′55″ W, rotenone, depth 7–27 m, J. T. Williams, S. Planes, E. Delrieu-Trottin, P. Sasal & J. Mourier. 9 Nov. 2011, right pectoral fin removed for tissue sample, tissue voucher specimen number MARQ-430 ( Fig. 1 ).

Paratypes (29 specimens, 6.9–32.5 mm SL). BPBM 12078 , 4 specimens, 1 male, 21.9 mm SL ( Figs. 2 , 8 ), 3 females, 15.2–24.1 mm SL, Marquesas, Hiva Oa, Head of Tahauku Bay , rocky shore and black sand, rotenone, depth 0–3 feet, J. & H. Randall, G. & A. Haywood & D. Bryant, 25 Apr. 1971 ; BPBM 12752 , female, 30.5 mm SL, Marquesas, Nuku Hiva, west side of Sentinelle de l’Est , rocky slope, no sand, quinaldine, depth 75 feet; J. Randall & D. Cannoy, 17 May 1971 ; USNM 409094 , male, 31.5 mm SL, same collection data as USNM 412487, right pectoral fin removed for tissue sample, tissue voucher specimen number MARQ-094 ( Fig. 3 ) ; USNM 409095 , male, 30.9 mm SL, same collection data as USNM 412487, right pectoral fin removed for tissue sample, tissue voucher specimen number MARQ-095 ; USNM 410662 , female, 25.5 mm SL, cleared and stained, same collection data as USNM 412487 ; USNM 411060 , male, 21.9 mm SL, Marquesas, northwest side of Mohotane Island , in a tiny partially protected cove, with about 6 foot swell breaking on point; rock wall extending from near shore break to about 20 m, collection made at base of rock wall and on sand and rubble at base. 9°57′01″ S, 138°49′55″ W, rotenone, depth 6–20 meters, J. T. Williams & S. Planes, 15 Oct. 2008, EtOH fixed, right pectoral fin removed for tissue sample, tissue voucher specimen number MOH-129 ( Fig. 4 ) ; USNM 411406 , male, 32.5 mm SL, Marquesas, Hiva Oa, northeast end of island on north side of Cap Matafenua , sand and rubble flat at the base of a rock wall at about 28 m. 9°44′32″ S, 138°48′32″ W, rotenone, 3–30 meters, J. T. Williams , S. Planes, E. Delrieu-Trottin, P. Sasal, J. Mourier, 12 Nov. 2011 ; USNM 412009 , juvenile, 11.5 mm SL, Marquesas, west coast of Mohotane Island , south of small bay in center of island, rocky point at south end of cove with about 8-foot swell, collection made along vertical rock wall and at base of rocky point in cave, 9°59′34″ S, 138°50′13″ W, rotenone, depth 6–25 meters, J. T. Williams & S. Planes, 17 Oct. 2008 ; USNM 412081 , female?, 16.7 mm SL, same collection data as USNM 412009, EtOH fixed, posterior 1/3 of specimen removed for tissue sample, tissue voucher specimen number MOH-211 ( Fig. 5 ) ; USNM 412180 , male?, 10.5 mm SL, same collection data as USNM 412009, EtOH fixed ; USNM 412487 , 16 specimens, 6.9–32.3mm SL, 6 females (26.0 mm SL, Figs. 7 , 9 ), 2 males (32.3 mm SL, Fig. 6 ), 8 juveniles, Marquesas, Nuku Hiva, Hatihou [Hatihe’u], 8°49′30″ S, 140°03′50″ W, rotenone, depth 3–6 meters, J. T. Williams , S. Planes, E. Delrieu-Trottin, P. Sasal, J. Mourier, M. Veuille, R. Galzin, T. Lison de Loma & G. Mou-Tham, 27 Oct. 2011 .

Diagnosis. Callogobius williamsi is distinguished from all other known Callogobius species by the following combination of characters: most or all scales cycloid, ctenoid scales (if present) restricted to mid-lateral region of caudal peduncle, 23–26 (usually 24 or 25) scales in lateral series; pelvic frenum present; preopercular papillae row (Row 20) absent; interorbital canal present with pair of pores B′, single pore D, and pair of pores F′.

Description. Holotype values indicated by an asterisk. Parentheses enclose number of type specimens with the particular value, counts made on both sides when applicable or possible. Dorsal fin rays VI, I,9 (20*); anal fin rays I,7 (20*), I,6 (1); pectoral fin rays 17 (7*), 18 (19), 19 (7); pelvic fin rays I,5 (44*); segmented caudal fin rays i7+7i (1), i8+7i (18*), 9+8 (1); procurrent rays 4+3 (12), 4+4 (7*); scales in lateral series 23 (4*), 24 (13), 25 (14*), 26 (3); predorsal scales 9 (1), 10 (8), 11 (9*); transverse scales 9 (1), 10 (5*), 11 (3); vertebral count 10+16 (based on x-rays of 10* adult specimens).

See Table 1 for selected morphometrics.

Scales large and deciduous, with distinctly outlined centres; most or all scales cycloid depending on individual; ctenoid scales, if present, usually only 2–3 on each side on mid-lateral region of caudal peduncle ( Fig. 8 ). Ctenii, when present, roughly triangular and pointed (not elongate) in groups of 1–10. Scales present in spaces between papillae rows on cheeks, preoperculum, and operculum, on lateral side of pectoral-fin bases, prepelvic and predorsal regions, and belly.

Teeth (based on one cleared and stained specimen, USNM 410662, 25.5 mm SL female) conical and slender; outer teeth on upper jaw slightly enlarged and curved; several tightly packed irregular rows of inner teeth decrease in number and converge posteriorly. Outer teeth in lower jaw slightly enlarged anteriorly; rows converged into single row posteriorly. Tongue (based on USNM 410662) moderately slender with blunt tip.

Anterior nostril moderately wide tube, reaching almost to outer edge of upper lip; posterior nostril upright tube of equal or just slightly shorter length. Two specimens over 15.0 mm SL appear to be missing both nostrils on one side.

Pelvic fins fully united forming disc, connecting membrane delicate and damaged on most specimens. All segmented pelvic-fin rays branched. Pelvic frenum present ( Fig. 6 ).

Urogenital papilla unpigmented in both sexes. Very long, slender in males; broad in females, without lateral projections ( Fig. 7 ).

Head pores: The following pores normally present in specimens above 15.0 mm SL. Interorbital canal with only five pores present: pair of posterior nasal pores (B′), single posterior interorbital pore (D), pair of anterior otic pores (F′). All specimens lack posterior portion of interorbital canal, preopercular canal, and temporal canal. Unusually high number of irregular pore patterns, even in specimens over 15.0 mm SL; in 6 of 17 specimens, anterior otic pore appears absent on one side; one specimen apparently without either posterior nasal pore. Pores present on larger juveniles (8.6–11.5 mm SL), sometimes with incompletely developed canals; absent on smaller juveniles (4.8–6.5 mm SL).

Papillae row configuration ( Fig. 9 ): Based on 17 specimens above 15.0 mm SL, observations recorded on each side where possible. Unusually high number of irregular papillae row patterns, most (at least 11 out of 17 specimens above 15.0 mm SL) with at least one irregularity, such as asymmetrical arrangements or rows with one or more breaks. Numbers of specimens observed with particular patterns are provided in parentheses; holotype values marked by an asterisk.

Postnasal rows (Row 2) separate and not joined across midline (16*) or irregular (1). Anterior suborbital row (Row 9) does not reach eye (34*) (space between row and eye about one-half length of row in most specimens); mid suborbital row (Row 10) does not reach eye (29) (space between row and eye more than one-sixth length of row) or nearly reaches eye (5*) (space between row and eye less than one-sixth length of row). Posterior suborbital rows (Row 11) separate with dorsal segment extending posteriorly beyond ventral segment (33*) or irregular (1). Longitudinal maxillary row (Row 14) unbroken (31*) or broken and irregular (3), extending posteriorly below (but not beyond) transverse cheek row (Row 13), which is short. Longitudinal mandibular row (Row 15) unbroken (32*) or broken and irregular (2). Approximately 11 (4*), 12 (29*), or 13 (1) transverse mandibular rows (Row 16) on each lower jaw; counts other than 12 unusual. Postorbital rows (Row 17) short and not joined, less than 3/4 length of distance from dorsal mid-line to bony edge of cranium (33*) or irregular (1). Preopercular row (Row 20) absent (34*).

Colour in preservative: Large specimens with intact scales and skin generally appear darkly mottled or speckled brown throughout head, body, and fins. Smaller specimens or those with missing scales may appear pale with mottling. General colour pattern consists of dark brown dorsal bars on lighter brown speckled body, but bars may blend into background colouration. Head markings poorly defined, consisting of wavy, reticulating patterns of dark and light brown. Ventral region of head lightly pigmented. Papillae rows more distinctly pigmented than surrounding regions. Dark bar (about 3–4 scales wide) extends dorsally over operculum and pectoral-fin base, towards first dorsal-fin spine. Dorsal bar (about 4 scales wide) extends below first dorsal fin; does not cross belly. Belly relatively pale. Narrow (about 2 scales wide), sometimes curved or irregular bar extends ventrally to mid-flank region below first 3–4 second dorsal-fin elements; Large irregular blotch present on each side anterior and ventral to bar. Wide, slanted bar (about 4–5 scales wide) extends below posterior portion of second dorsal fin to posterior edge of anal fin and around anterior portion of caudal peduncle; bar narrows ventrally. Narrower bar (about 3 scales wide) encircles posterior caudal peduncle, edge of hypural plate, and proximal regions of caudal fin. First dorsal fin dark with wavy horizontal lines and reticulations, lighter near spine tips. Second dorsal fin with broad wavy horizontal lines, blotches, and reticulations; very dark line starting at mid-upper anterior edge sloping posteroventrally. Caudal fin dark with wavy vertical markings, converging near upper anterior edge, sometimes appearing spot-like. Pectoral fins darkly mottled with wavy vertical markings. Pelvic and anal fins dark with fine speckles; posterior portion of anal fin with slanted wavy dark lines.

Fresh colouration: Similar to preserved specimens, with some specimens exhibiting yellowish pigment in lighter areas of fins, head, and body. Caudal markings often converging anterodorsally, sometimes creating caudal spot but often difficult to distinguish.

Etymology. Named in honour of Dr. Jeffrey Williams who collected the holotype and recognized it as a new species. Suggested vernacular name: Williams’s flapheaded goby.

Distribution and habitat. Collected only from the Marquesas Islands, a region known for a high level of endemicity ( Randall & Earle 2000; Delrieu-Trottin et al. 2015). J. Williams (pers. comm.) collected this species in areas of dark grey to black rock walls, where water tends to be cooler due to upwelling. His team did not collect this species in sheltered coral reefs. J. Williams (pers. comm.) reports spreading rotenone along the rocky slope and on the sandy area at the base of the rocky slope or wall. The specimens would come out and drop onto the sandy area where divers would gather them.

Comparisons. At least two other species of Callogobius occur in French Polynesia, Callogobius sclateri ( Steindachner, 1879) and a species provisionally identified as C. maculipinnis ( Fowler, 1918) (awaiting a review of the maculipinnis species group; see Delventhal et al. 2016). Callogobius williamsi is distinguished from C. sclateri by its mostly dark body colour vs. distinct contrasting bars, a darker area or black spot present on the caudal fin (not always visible due to dark fin colouration) vs. black spot absent on the caudal fin, pelvic fins united with a frenum vs. separate without a frenum, preopercular row (Row 20) absent vs. present, few or no ctenoid scales present vs. ctenoid scales distributed over the posterior portion of the body, and caudal fin usually longer than head length vs. shorter than head length. Callogobius williamsi is distinguished from all species in the C. maculipinnis species group by a darker area or black spot present on the caudal fin (not always visible due to dark fin colouration) vs. black spot absent on the caudal fin, preopercular and temporal canals absent vs. preopercular and temporal canals present, chin with 11 or more transverse mandibular papillae rows (Row 16) vs. chin with 4 or fewer transverse mandibular papillae rows (Row 16), few or no ctenoid scales present vs. ctenoid scales distributed over the posterior portion of the body, and caudal fin usually longer than head length vs. shorter than head length in specimens> 20 mm SL. See species diagnosis for characters distinguishing C. williamsi from all other known species of Callogobius .

Figures

FIGURE 1. Callogobius williamsi sp. nov., holotype, USNM 409430, female, 32.9 mm SL, fresh colouration. The pale grey film behind the eyes and below the throat is mucus. Note that the right pectoral fin is prominently visible extending over the back of the specimen and should not be confused with the first dorsal fin, which is pressed against the back. A patch of scales is missing posterior to the origin of the second dorsal fin on the caudal peduncle, resulting in lighter colouration in that area. The darker area on the caudal fin, indicated by the arrow, partially blends into the brown pattern of the fin. Photo by J.T. Williams.

FIGURE 2. Callogobius williamsi sp. nov., paratype, BPBM 12078, male, 21.9 mm SL: A. Fresh pattern from black and white photograph, arrow indicates dark area on anterodorsal portion of caudal fin. Photo by J.E. Randall; B. Preserved pattern after 50 years in isopropyl alcohol. Photo by R.D. Mooi.

FIGURE 3. Callogobius williamsi, sp. nov., paratype, USNM 409094, male, 31.5 mm SL, fresh colouration, dorsolateral view. The pale brown film at either side of the mouth is mucus. Note that the right pectoral fin is prominently visible extending over the back of the specimen and should not be confused with the first dorsal fin. Photo by J.T. Williams.

FIGURE 4. Callogobius williamsi, sp. nov., paratype, USNM 411060, male, 21.9 mm SL, fresh colouration, with some superficial damage (missing scales and torn fin membranes). Note that the left pectoral fin extends dorsally over the back and should not be confused with the first dorsal fin. The black spot on the upper portion of the caudal fin indicated by the arrow. Photo by J.T. Williams.

FIGURE 5. Callogobius williamsi sp. nov., paratype, USNM 412081, subadult, 16.7 mm SL, fresh colouration. Note that this is a dorsoventral view; the right pectoral fin extends dorsally and should not be confused with the first dorsal fin which is also discernible. Photo by J.T. Williams.

FIGURE 6. Ventral view of the pelvic fin of Callogobius williamsi sp. nov., paratype, USNM 412487, male, 32.3 mm SL. Scale bar = 2 mm. Illustration by R.D. Mooi.

FIGURE 7. Ventral view of the urogenital papilla of Callogobius williamsi sp. nov., paratype, USNM 412487, female, 26.0 mm SL. Scale bar = 1 mm. Illustration by R.D. Mooi.

FIGURE 8. Distribution of ctenoid scales on the mid-lateral region of the caudal peduncle of Callogobius williamsi sp. nov., paratype, BPBM 12078, male, 21.9 mm SL: A. General view, ctenoid scales in grey; B. Detailed view of scale morphology of the same specimen. Ctenoid scales shown in grey, scale architecture shown only for complete scales. Scale bars = 1 mm. Illustrations by R.D. Mooi.

FIGURE 9. Sensory pore and papillae pattern on the head of Callogobius williamsi sp. nov., paratype, USNM 412487, female, 26.0 mm SL: A. Dorsal view. B. Lateral view. C. Ventral view. Letter abbreviations of sensory pores follow Akihito & Meguro (1977) and descriptive names are modified from Takagi (1957) following Delventhal et al. (2016). Papillae row numbering follows Akihito & Meguro (1977) and descriptive names are from Delventhal & Mooi (2013). Sensory pores: B′ = posterior nasal; D = posterior interorbital; F′ = anterior otic. Papillae rows: 2 = postnasal; 9 = anterior suborbital; 10 = mid suborbital; 11 = posterior suborbital; 13 = transverse cheek; 14 = longitudinal maxillary; 15 = longitudinal mandibular; 16 = transverse mandibular; 17 = postorbital; 21 = transverse opercular. Note: The longitudinal maxillary row (Row 14) is divided into two segments in this specimen; in most specimens of C. williamsi, this row is continuous. The majority of C. williamsi specimens we have examined have at least one papillae row with atypical arrangement. Scale bar = 2 mm. Illustrations by R.D. Mooi.