Mephisto fraserbrunneri Tyler 1966

Bemis, Katherine E., Tyler, James C., Psomadakis, Peter N., Ferris, Lauren Newell & Kumar, Appukuttannair Biju, 2020, Review of the Indian Ocean spikefish genus Mephisto (Tetraodontiformes Triacanthodidae), Zootaxa 4802 (1), pp. 82-98 : 90-94

Mephisto fraserbrunneri Tyler 1966

Devil’s Spikefish

Mephisto fraserbrunneri Tyler 1966a: 1–5 (original description; based upon a single specimen, holotype: ANSP 103314, type locality: eastern Bay of Bengal , Andaman Sea , off southern Myanmar, Indian Ocean, 10°39′N, 97°06′E, R/ V Anton Bruun, Station 22B, 159 fathoms (= 290 m), 24 March 1963; etymology: species named in honor of A. Fraser-Brunner for his pioneering revisions of many families of plectognaths). Tyler, 1966b: 4 (considered to be a generalized triacanthodid). Tyler, 1968: 133–138 (description, proposed relationships, illustration of pelvis and scales, photograph of BAH IOES-201 (= ZMH 5629)). Tyler, 1980 (summary of proposed relationships as given in Tyler (1968)). Shcherbachev et al., 1986: 208 (description of USNM 350153; specimen identified as Mephisto sp. because scales have several spinules that are bifurcate). Tyler, 1986: 887 ( Mephisto included in key). Gorelova et al., 1993: 225 (mesobenthic species, captured on Error Seamount; stomach contents of 105 mm SL specimen (now USNM 350153) contained chitin fragments and peropods of a gammarid). Manilo and Bogorodsky, 2003: S123 (listed only). Matsuura, 2015: 75, 76 (range includes Somalia, Arabian Sea, and Andaman Sea). Mullasseri et al., 2017: 76–81 (comparison of seven specimens from Andaman Islands of putative Paratriacanthodes retrospinis with data from Tyler (1968) on M. fraserbrunneri , but critical diagnostic measurements, such as length of gill opening, not provided, and the single specimen illustrated (figs. 2, 3, both in color; fresh and after preservation of the same specimen) of putative P. retrospinis has the typical blotchy color pattern and long gill opening that is diagnostic of M. fraserbrunneri rather than the horizontally lined pattern and shorter gill opening typical of P. retrospinis ; these specimens require re-examination for proper identification). Matsuura et al., 2018: 30–33 (comparison of M. fraserbrunneri with M. albomaculosus ).

Material. Known from the holotype ANSP 103314, seven additional specimens, and two separate photographic records of individuals that were not retained ( Table 1).

Diagnosis. A species of Mephisto with red to pink coloration and lighter, almost white, areas and darker red blotches; the ventral part of the head and body beginning under the eye is light in coloration, but no white, rounded markings are present ( Fig. 1 A–D). Pelvic width 10.6–12.1% SL; pelvic width into pelvic length 2.6–3.2 times; gill rakers 16–19; pseudobranch lamellae 17–20.

Description. Data on meristics ( Table 2), proportional measurements ( Table 3), and additional characters ( Table 4 ) are summarized for all eight specimens.

Coloration. Mephisto fraserbrunneri is red to pink with lighter, almost white, areas and darker red blotches ( Fig. 1 A–D). The darkest red regions are below the spinous dorsal fin, below the posterior part of the soft dorsal fin, and above the pectoral fin from behind the eye. The ventral part of the head, beginning under the eye, is light in coloration. The spinous dorsal fin is predominantly dark red, whereas the soft dorsal and anal fins are white proximal to the body and darker distally. In alcohol, the blotchy pattern remains, and the darkest red areas in life are brown ( Fig. 4A ). The peritoneum and branchial cavity are tan to blackish and speckled with darker spots ( Table 4 ).

Description of scales during ontogeny. The scales of Mephisto fraserbrunneri begin with a single spinule and increase in number of spinules during their ontogeny; the branching of spinules also increases with specimen length. Matsuura et al. (2018: fig 2) described the scales of M. albomaculosus as differing from those of M. fraserbrunneri because the scales of M. albomaculosus have a bifurcate spinule at the base of the central spinule ( Fig. 5D ). However, the new specimens reported herein increase the size range known for M. fraserbrunneri , and we now have more information on how the number of spinules and their branches change throughout ontogeny ( Table 4 ). We confirm that large M. fraserbrunneri (DABFUK/FI/ 302, 102.7 mm SL and USNM 350153 105.8 mm SL) have up to six spinules per scale, with 1–3 branched spinules and the central and largest spinule having a bifurcate spinule at the base ( Fig. 5 ). Thus, having a bifurcate spine on the central spinule is not diagnostic for Mephisto species. Shcherbachev et al. (1986) identified USNM 350153 as Mephisto sp. because at the time it was collected and examined only two small specimens of Mephisto fraserbrunneri were known, and each had scales with a single, unbranched spinule; we recognize the multiple spinule pattern present in the largest specimens as representing an advanced stage of ontogeny ( Fig. 5 A–C).

Description of teeth and tooth replacement. Mephisto has relatively few stoutly conical teeth that are larger in the anterior part of the jaw and smaller posterolaterally on the premaxilla and dentary ( Table 2; Fig. 6 ). Teeth are re- placed intraosseously ( Fig. 6 ). Teeth develop underneath functional teeth and erupt on the labial side of the jaw. There is no obvious pattern of replacement; several teeth in the jaws of various specimens were in the process of replacement. For example, in the specimen shown in Figure 6 , there are nine teeth in both the left and right premaxillae; two or three teeth are undergoing replacement (loci 3 and 7 in the left premaxilla; loci 1, 3, and 9 in the right premaxilla). On each side of the left and right dentary there are 11 teeth; two to four teeth are undergoing replacement (loci 2 and 10 on the left dentary and loci 1, 3, 7, and 9 on the right dentary). In the right dentary, locus 1 has an eroding tooth and an erupting replacement tooth beneath it.

Diet. Three specimens of Mephisto fraserbrunneri had stomach contents: DABFUK/FI/304 contained primarily foraminiferans and secondarily pteropods. Both planktic ( Globorotalia menardii, Globigerinella siphonifera, Globigerinoides ruber , Neogloboquadrina dutertrei , and Trilobatus sacculifer ) and benthic ( Bolivina and Uvigerina ) foraminiferans were present (Brian Huber, pers. comm., 2020). Pteropod shells, as well as several scaphopods and an echinoderm spine, were also in the stomach. The shells of these organisms had sediment on them, and the foraminiferans did not appear to have been ingested alive. USNM 306629 had well-digested amphipods in its stomach. The largest specimen, USNM 350153, had chitin fragments and peropods of a gammarid in its stomach ( Gorelova et al., 1993), which were lost when it was cleared and stained. Based upon this data, we conclude that M. fraserbrunneri feeds on a diversity of small organisms found on or in bottom sediment.

Geographic and depth distribution. The holotype of Mephisto fraserbrunneri was collected in the Andaman Sea off Myanmar. Three of the eight known specimens of M. fraserbrunneri were collected off Somalia. The four most recently collected specimens of M. fraserbrunneri were caught off Kerala on the southwest coast of India in the Lakshadweep Sea ( Fig. 2 ). All eight specimens of M. fraserbrunneri were caught in bottom trawls at depths of 176–415 m ( Table 1) .

Figures

FIGURE 1. Color photographs of Mephisto. See Table 1 for collection localities. A. Mephisto fraserbrunneri, University of Kerala DABFUK/FI/301, 64.5 mm SL. Photograph by A. Biju Kumar. B. Mephisto fraserbrunneri, University of Kerala DAB- FUK/FI/303, 64.2 mm SL. Photograph by A. Biju Kumar. C. Mephisto cf. fraserbrunneri, specimen not retained, est. 54 mm SL. Photograph by Oddgeir Alvheim. D. Mephisto cf. fraserbrunneri, specimen not retained, est. 89 mm SL. Photograph by Tom Williams. E. Mephisto albomaculosus, holotype, NSMT-P 132271, 94.4 mm SL. Photograph by Oddgeir Alvheim, from Matsuura et al. (2018), photograph reprinted with permission from the Ichthyological Society of Japan. F. Mephisto cf. albomaculosus, specimen not retained, est. 94 mm SL. Photograph by Oddgeir Alvheim, from Matsuura et al. (2018), photograph reprinted with permission from the Ichthyological Society of Japan.

FIGURE 2. Distribution and habitat of Mephisto. A. All known records of Mephisto, including holotypes of M. fraserbrunneri and M. albomaculosus, non-type specimens of M. fraserbrunneri, and photographic records of specimens that were not retained. B. Detail of region in white box in part A highlighting collection localities on continental shelf off Somalia and Socotra, and Error Seamount (part of the Carlsberg Ridge). Bathymetric data from Smith and Sandwell (1997).

FIGURE 4. Mephisto fraserbrunneri, University of Kerala DABFUK/FI/301, 64.5 mm SL. A. Specimen in alcohol. White arrows indicate the length of the gill opening, which is the diagnostic character for Mephisto. B. Radiograph of same specimen. Images by Sandra Raredon.

FIGURE 5. Mid-body scales of Mephisto. Anterior to left. A–C Mephisto fraserbrunneri, USNM 350153, 105.8 mm SL. A. Patch of scales. White arrows indicate tips of bifurcate spinules at base of central spinules; black arrows indicate tips of central spinules. B. Single scale showing five spinules, including a central spinule with a bifurcate spinule at its base and both branched and unbranched dorsal and ventral spinules. White arrows indicate tips of single or bifurcate spinules; black arrow indicates central spinule tip. C. Illustration of single scale from M. fraserbrunneri to show relative length of spinules when viewed obliquely and for comparison with images B and D. D. Illustration of a single scale of M. albomaculosus, NSMT-P 132271, 94.4 mm SL. Illustration from Matsuura et al. (2018), reprinted with permission from the Ichthyological Society of Japan. Note, scale has been reflected so image faces left. In large specimens of both M. fraserbrunneri and M. albomaculosus the central spinule has a bifurcate branch. Apparent differences in shape of scale plates in parts C and D is because the regions of overlap are not shown in part D.

FIGURE 6. Micro-CT scan of jaws and dentition of Mephisto fraserbrunneri, ZMH 5629, 66.0 mm SL. Tooth loci with developing teeth are indicated with stars, and an eroding tooth is indicated with an E. A. Anterior view showing intraosseous tooth replacement in left and right premaxillae and dentaries. B. Lateral view of teeth developing intraosseously that are nearing eruption.

Tables

TABLE 4. Qualitative characters for the eight examined specimens of Mephisto fraserbrunneri. Dashes indicate data that could not be obtained because of specimen damage or specimen having been cleared and stained prior to this study. Asterisk indicates data taken from Shcherbachev et al. (1986).

Character	DABFUK/ FI/304	ANSP 103314 Holotype	DABFUK/FI/303	DABFUK/FI/301	ZMH 5629	USNM 306629	DABFUK/FI/302	USNM 350153
Standard Length (mm)	48.6	52.2	64.2	64.5	66.0	68.8	102.7	105.8
Number of upright spinules on scales	1 central, unbranched spinule; no bifurcate spinule at base	1 central, unbranched spinule; no bifurcate spinule at base	3 spinules; central spinule frequently with one branch; dorsal and ventral spinules unbranched	3 spinules; central spinule frequently with one branch; dorsal and ventral spinules unbranched	3 spinules; central, dorsal, and ventral spinules all unbranched	3 or 4 spinules; central, dorsal, and ventral spinules all unbranched	4–6 spinules; central spinule with birfucate spine at base; branching in 1 or 2 of dorsal and ventral spinules	4 or 5 spinules; central spinule with birfucate spine at base; branching in 1 or 2 of dorsal and ventral spinules
Gill opening extension	Well below pectoral-fin base	Slightly below pectoral-fin base	Well below pectoral-fin base	Slightly below pectoral-fin base	Slightly below pectoral-fin base	Slightly below pectoral-fin base	Well below pectoral- fin base	Level of lower margin of pectoral-fin base*
Pseudobranch extension	—	Upper origin of pectoral-fin base	—	Upper origin of pectoral-fin base	Upper origin of pectoral-fin base	Upper origin of pectoral-fin base	Upper origin of pectoral-fin base	Above upper origin of pectoral-fin base
Retrose barbs	Present on 1st dorsal and pelvic spine	Present on 1st dorsal and pelvic spine	Present on 1st dorsal and pelvic spine	Present on 1st dorsal and pelvic spine	Present on 1st dorsal and pelvic spine	Present on 1st dorsal and a few on pelvic spine	Present on 1st dorsal and pelvic spine	Dorsal spine broken, pelvic spine without retrose spines
Peritoneum color	Blackish	Dark tan with darker speckles	Blackish	Dark tan with dark speckles	Tan with darker brown speckles	Dark tan with darker speckles	Blackish	—
Brachial cavity color	Blackish	Dark tan	Blackish	Dark tan	Tan	Tan	Blackish	—
Sex based on gonads	?	Immature	Female (?)	Male	Female	Male (?)	Mature female	—