江蘇安徽早三疊世裂齒魚科一新種：吳氏三疊魚

Teffichthys wui sp. nov.， a new perleidid fish from the Early Triassic of Jiangsu and Anhui， China

Abstract Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here， we report the discovery of a new perleidid， Teffichthys wui sp. nov.， based on six wellpreservedspecimens from the late Smithian （Olenekian， Early Triassic） marine deposits ofJurong， Jiangsu and Chaohu， Anhui， China. This new discovery documents the third and youngestspecies of Teffichthys， which is slightly younger than the Dienerian （Induan） T. elegans fromGuizhou and the early Smithian T. madagascariensis from Madagascar. The new species showsdiagnostic features of Teffichthys （presence of a spiracular， 38–41 lateral line scales， and no morethan three epaxial rays in the caudal fin） but differs from T. madagascariensis and T. elegans insome autapomorphies （e.g.， a horizontal opercle/subopercle contact and smooth scales with anearly straight posterior margin）. The diagnostic features for the genus Teffichthys and the familyPerleididae are emended based on detailed comparisons of the new taxon with other perleidids.The phylogenetic relationships of perleidids with other stem neopterygians are discussed using acladistic approach， and the results provide new insights into the phylogeny and classification ofmain stem neopterygian clades.

Key words Jiangsu， Anhui， Early Triassic， Perleidiformes， osteology， phylogeny

Citation Xu G H， Yuan Z W， Ren Y et al.， 2024. Teffichthys wui sp. nov.， a new perleidid fish from the Early Triassic of Jiangsu and Anhui， China. Vertebrata PalAsiatica， 62（3）：165–185

1 Introduction

Neopterygii is the most taxonomically rich group of ray-finned fishes and is composed ofHalecomorphi， Ginglymodi， Teleostei and closely related fossil taxa （Regan， 1923; Schultze，1966; Patterson， 1973; Gardiner and Schaeffer， 1989; Arratia， 1999; Coates， 1999; Hurleyet al.， 2007; Cavin， 2010; Grande， 2010; Clarke and Friedman， 2018; Xu， 2021a， b）. This group underwent rapid early radiation in the Early Triassic， with many stem neopterygiansand parasemionotid halecomorphs recovered from Spitsbergen， East Greenland， Madagascar，West Canada， the USA， India， Central Siberia and China （Stensi?， 1921， 1932; Nielsen， 1949;Lehman， 1952; Su， 1981; Sytchevskaya， 1999; Xu et al.， 2015; Romano et al.， 2016， 2017;Marramà et al.， 2017; Yuan et al.， 2022）. Studies of these taxa are important for understandingthe early diversification of Neopterygii and the biological recovery in the aftermath of the end-Permian mass extinction （Chen and Benton， 2012; Benton et al.， 2013; Dai et al.， 2023）.

Traditionally， stem neopterygians were referred to the order Subholostei （Brough， 1939;Schaeffer， 1956; Patterson， 1973）， or most of them to the order Perleidiformes （Hutchinson，1973; Bürgin， 1992， 1996; Neuman and Mutter， 2005; López-Arbarello and Zavattieri， 2008;Sun et al.， 2008， 2009）. Up to 13 families were once assigned to Perleidiformes， and thismade the grade notoriously paraphyletic （Yuan et al.， 2022）. Recent phylogenetic studiesconstrict the Perleidiformes to include only the family Perleididae， and the classification ofstem neopterygians is being reassessed （Xu et al.， 2015; Wen et al.， 2019; Xu， 2021a， b; Shenand Arratia， 2022; Yuan et al.， 2022）. The genus Teffichthys is a marine stem neopterygiantaxon， including two species in the Early Triassic， the type species T. madagascariensis fromthe early Smithian of Madagascar （Lehman 1952; Marramà et al.， 2017）， and T. elegansfrom the Dienerian （Induan） of Guizhou， China （Yuan et al.， 2022）. The type species wasoriginally referred to as Perleidus （Piveteau， 1934）， a genus that now includes two MiddleTriassic species， P. altolepis， from the Ladinian of Perledo and Monte San Giorgio areas inItaly and Switzerland （Deecke， 1889; Lombardo， 2001）， and P. sinensis from the Anisian ofLuoping， eastern Yunnan in China （Lombardo et al.， 2011）. Marramà et al. （2017） namedTeffichthys to accommodate ‘Perleidus’ madagascariensis， and placed the genus in thesubclass Acintopterygii without reference to a particular family or order; however， a recentphylogenetic study （Yuan et al.， 2022） supported the placement of Teffichthys in the Perleididae（Perleidiformes）.

Here， we report the discovery of a new species of Teffichthys based on six well-preservedspecimens， four from the Lower Qinglong Formation exposed at the Qingshan section inJurong City， Jiangsu Province and two from the Helongshan Formation at the Majiashansection in Chaohu City， Anhui Province （Fig. 1）. Studies of conodont biostratigraphy indicatethat the fossil beds in both sections are coeval， with a late Smithian， Olenekian， Early Triassicin age （Liu et al.， 2020）. In addition to the new species of Teffichthys， other bony fishes knownfrom the same fossil beds include a coelacanth， another perleidid （Plesioperleidus yangtzensis）and several parasemionotids （Qian et al.， 1997; Liu et al.， 2002; Jin et al.， 2003; Tong et al.，2006）. The fish fossils are preserved in calcareous nodules embedded in black shales andmudstones. Taphonomic studies suggest that fish nodules were formed in a calm and euxinicenvironment with the participation of a vast array of microbes and possibly sulfur-reducingbacteria （Qiu et al.， 2019）.

2 Materials and methods

The studied material of the new species of Teffichthys includes four specimens storedat the fossil collections of the Institute of Vertebrate Paleontology and Paleoanthropology，Chinese Academy of Sciences （IVPP） in Beijing， and two specimens （previously referred toPlesioperleidus jiangsuensis; Tong et al.， 2006） at the YiFu Museum of China University ofGeoscience （CUGM） in Wuhan. All specimens were prepared by air-chisels， accompaniedoccasionally with sharp steel needles. The relative position of fins and scale counts wereexpressed following Westoll （1944）. The traditional actinopterygian nomenclatures （e.g.，Gardiner and Schaeffer， 1989; Bürgin， 1992; Xu， 2020a） are generally followed for ease ofcomparison with most of the existing literatures.

The phylogenetic framework for the discussions provided herein is based on the resultsof a phylogenetic analysis including 144 morphological characters and 60 actinopterygiantaxa （see the electronic supplementary material）. The characters were adopted mainly fromXu （2021a） and Yuan et al. （2022）. All characters were unordered and equally weighted. Thebasal actinopterygian Moythomasia durgaringa （Gardiner， 1984） was selected as the out-grouptaxon. The data matrix was generated by WinClada 1.00.08 （Nixon， 2002）. Tree searches wereaccomplished with the heuristic search algorithm （gaps treated as missing data; 1000 randomaddition sequence replicates; tree bisection-reconnection （TBR） branch-swapping， with 10trees held at each step and multiple trees saved） in PAUP* 4.0a169 （Swofford， 2003）.

Anatomical abbreviations an， anterior nostril; ang， angular; ao， antorbital; apl， anteriorpit-line; bf， basal fulcra; br， branchiostegal ray; cl， cleithrum; den， dentary; dhy， dermohyal;dpt， dermopterotic; dsp， dermosphenotic; es， extrascapular; ff， fringing fulcra; fr， frontal; gu，gular; io， infraorbital; lgu， lateral gular; mpl， middle pit-line; mx， maxilla; n， nasal; op， opercle;pa， parietal; pcl， postcleithrum; pf， principle fin ray; pmx， premaxilla; pn， posterior nostril; pop，preopercle; ppl， posterior pit-line; pra， proximal radial; prr， procurrent ray; pt， posttemporal; r，rostral; scl， supracleithrum; scr， sclerotic ring; so， suborbital; sop， subopercle; spi， spiracle; su，supraorbital.

3 Systematic paleontology

Subclass Actinopterygii Cope， 1887

Superdivision Neopterygii Regan， 1923

Order Perleidiformes Berg， 1937

Family Perleididae Brough， 1931

Emended diagnosis A family distinguished from other stem neopterygians by thefollowing unique combination of features： two to five supraorbitals; single suborbitalconfined between dermosphenotic and preopercle; suborbital half-length of anterior marginof preopercle; opercle no larger than subopercle; preopercle/maxilla contact nearly equal toanterior margin of subopercle in length; supracleithrum slightly deeper than posterior marginof opercle; five or six pairs of branchiostegal rays; no more than seven epaxial rays in caudalfin; no more than 51 lateral line scales.

Content Perleidus De Alessandri， 1910; Meidiichthys Brough， 1931; Plesioperleidus Suamp; Li， 1983; Plesiofuro Su， 1993; Paraperleidus Zhao amp; Lu， 2007; Luopingperleidus Geng etal.， 2012; Teffichthys Marramà et al.， 2017.

Genus Teffichthys Marramà et al.， 2017

Emended diagnosis A genus of Perleididae distinguished from other genera of thisfamily by the following features： presence of spiracular; narrow dermopterotic/preoperclecontact; 38–41 lateral line scales; and no more than three epaxial rays in caudal fin.

Teffichthys wui sp. nov.

（Figs. 2–6）

Etymology The specific epithet wui is dedicated to Mr. Wu Zi-Hao， who contributed to the fossil collection of the holotype （IVPP V27614）.

Holotype IVPP V27614， a relatively complete specimen with part of caudal fin missing，from Qingshan Village， Jurong City， Jiangsu Province.

Referred specimens IVPP V30880， 30881， 30887 from Qingshan， Jurong， Jiangsu;CUGM J2201 and J2202 from Majiashan， Chaohu City， Anhui Province.

Locality and horizon Jurong， Jiangsu， Lower Qinglong Formation; Chaohu， Anhui，Helongshan Formation. Smithian， Olenekian， Early Triassic （Qiu et al.， 2019; Liu et al.， 2020）.

Diagnosis A new species of Teffichthys distinguished from other species of this genusby the following features： three supraorbitals; horizontal contact of opercle with subopercle;absence of anterodorsal process of subopercle; 17 dorsal fin rays; smooth scales with nearlystraight posterior margin; and pterygial formula of D23/P16， A22–23， C33/T38.

4 Description

General morphology and size Similar to those of other species of Teffichthys， T. wui hasa blunt snout， a fusiform body and an abbreviated heterocercal caudal fin. Among the studiedspecimens， the holotype （Fig. 2A） is the most complete one， having a standard length （thelength from the tip of the snout to the posterior extremity of the caudal peduncle） of 96 mm.The head length （27 mm） is slightly smaller than the greatest body depth （31 mm）， whichlies midway between the posterior margin of the opercle and the origin of the dorsal fin. Thelargest known specimen （IVPP V30880） has a length of 108 mm from the tip of the snout tothe origin of the ventralmost caudal ray （Fig. 2B）. The fragile skeletons are easily broken away during preparation， and the ornamentations of cranial bones are usually poorly-preserved. Theendocranium and palatine are unknown because of lateral compression. The caudal fin cannotbe reconstructed because of incomplete preservation， and the vertebral column is not visibledue to the squamation in situ.

Snout The median rostral is shield-like， being the largest bone of the snout region （Fig. 3D）.The depth of the bone is 68% of the length of the frontal. It has a rounded ventral margin， a slightly convex dorsal margin， and curved lateral margins. Each lateral margin of the rostralhas a big notch for the anterior nostril. The remaining lateral margin of the rostral sutures withthe medial margins of the nasal and the antorbital. The anterior ethmoid commissure of thelateral line system is enclosed in the rostral， indicated by two short canals at the anteroventralportion of this bone （Fig. 3D）.

The nasals are relatively large， deeper than wide， with its lateral margin forming the mostpart of the anterior orbital margin （Fig. 3B， D）. The medial margin of the bone is notched forthe anterior nostril at its middle portion， and the ventral portion of the lateral margin bears anotch indicating the position of the posterior nostril. An anterior portion of the supraorbitalsensory extends anteroventrally at the dorsal portion of the nasal， and ends at the level of thenostril notches （Fig. 3B）.

The antorbitals are small and quadrangular， defining the anteroventral margin of theorbit （Fig. 3B， D）. The sensory canal is not discernable in the bone because of poor state ofpreservation.

Skull roof The skull roofing bones include a pair of frontals， parietals， dermopterotics，and extrascapulars （Figs. 3， 4）. The frontal is nearly trapezoidal with a relatively narrowportion anterior to the orbital center and a slightly concave posterior margin; it graduallywidens posteriorly， reaches its maximal width near the posterior orbital margin， and then becomes slightly narrow posterior to the orbit. The medial suture between frontals is nearlystraight.

The parietal is rectangular， longer than wide， being about two-thirds of the frontal length（Figs. 3， 4）. Each parietal contacts the frontal anteriorly， the dermopterotic laterally， and theextrascapular posteriorly. The dermopterotic is elongate， about 1.5 times as long as the parietal.It tapers anteriorly and inserts between the frontal and dermosphenotic. The extrascapular istrapezoidal， contacting the parietal and dermopterotic anteriorly. It tapers medially and reachesthe middle line of the skull.

The supraorbital canal extends longitudinally through the frontal， enters the parietal andends at the anterior portion of this ossification. Three short pit-lines are discernable in theparietal， including a straight anterior pit-line， a curved， anterolaterally extended middle one，and a posterolaterally extended posterior one （Fig. 4A）. The temporal sensory canal extendsparallel to the lateral margin of the dermopterotic， and enters the extrascapular posteriorly（Fig. 3D）. Additionally， the supratemporal commissure runs transversely through the middleportions of both extrascapulars.

Circumorbital bones There are three supraorbitals flanking the lateral margin of thefrontal （Fig. 3B）. They are rectangular; the first （anteriormost） is slightly longer than the lastone， and the middle one is the shortest （Fig. 3D）.

Two infraorbitals are present. The first infraorbital is elongate and tube-like， forming mostof the ventral border of the orbit （Fig. 4C）. The second is crescent， transferring the infraorbitalsensory canal into the dermosphenotic （Figs. 3D， F， 4B）.

The dermosphenotic is narrow and deep， forming the posterodorsal margin of the orbit.Posterior to the dermosphenotic， there is a suborbital， which is rectangular， as deep as thedermosphenotic （Figs. 3D， 4C）. More posteriorly， an elongate， trapezoidal ossification insertsbetween the preopercle and dermopterotic. This ossification is labeled as the spiracular （Fig. 4C）following the traditional terminology in Teffichthys （Lehman， 1952; Marramà et al.， 2017）.

Thin sclerotic bones are partly preserved near the orbital rim， but their number andcomplete shape are still unknown because of incomplete preservation （Fig. 3D）.

Jaws The premaxillae are small and poorly preserved. A right premaxilla is partlyexposed in IVPP V30880 （Fig. 3D）; it is nearly trapezoidal with two conical teeth discernableat its oral margin， and the actual tooth number could be slightly higher （Fig. 5）. The maxillahas an elongated infraorbital ramus and a trapezoidal postorbital blade （Figs. 3， 4）. The lengthof the maxilla is 2.5–2.7 times its maximum depth. The posterior margin of the maxilla isrounded， and the tooth-bearing margin is slightly concave. The teeth are distributed only atthe infraorbital ramus of the bone. There were 25 peg-like teeth preserved in the maxilla ofV30880 （Fig. 3D）. The posterior teeth are slightly shorter than the anterior teeth.

The lower jaw is wedge-shaped with two elements， dentary and angular， discernable inlateral view （Figs. 3D， 4C）. The supra-angular， commonly present in other stem neopterygians，is not exposed probably because of its small size and the lateral coverage of the maxilla. The dentary is large and stronger than the infraorbital ramus of the maxilla， being 88% of themandibular length. The oral margin of the dentary is slightly concave， bearing 24 peg-like teethin V30880 （Fig. 3D）. The teeth are nearly equal to those of the maxilla in size. The angularis small and elongate， accounting a quarter of the mandibular length. The mandibular canalextends through the dentary and angular， indicated by a longitudinal canal and a line of smallpores parallel to the ventral margin of the dentary， and a curved canal in the angular （Fig. 3D）.

The prearticular is plate-like， bearing some blunt， molariform teeth on its oral margin （Fig. 4B）.No other ossifications are discernable from the medial surface of the lower jaw.

Opercular series and dermohyal The opercle and subopercle are trapezoidal， and thecontact suture between them is nearly horizontal. The subopercle is approximately 1.5 times asdeep as the opercle. It has a straight dorsal margin， lacking an anterodorsal process （Figs. 3， 4）.An interopercle is absent， as in other stem neopterygians. The vertically oriented preopercleis deep and quadrangular， with a tapering ventral portion inserting between subopercle andmaxilla. The anteroventral margin of the preopercle that contacts the posterodorsal margin ofthe maxilla is nearly equal to the anterior margin of the subopercle in length. The preopercularsensory canal is indicated by a vertical line of small pores close to the posterior margin of thisbone. Additionally， a dermohyal is wedged between the preopercle and opercle. It is small andtriangular （Fig. 3）.

Branchiostegal rays and gulars A lateral gular and five branchiostegal rays arediscernable from the left side of the skull in IVPP V30880 （Fig. 3D）. The anterior bone isidentified as a lateral gular because it is slightly broader than the anteriormost branchiostegalray， similar to the condition in Plesiofuro （Xu et al.， 2015）. The lateral gular and anterior fourbranchiostegal rays are elongate and rectangular， and the posteriormost branchiostegal ray isbroad and triangular （Fig. 3）. A detached median gular is preserved near the branchiostegalrays; it is heart-shaped， nearly half of the length of the lower jaw （Fig. 4C）.

Paired girdles and fins A posttemporal， a supracleithrum， a cleithrum and twopostcleithrae are present on each side of the pectoral girdle. The posttemporal is broadand trapezoidal， nearly as wide as the extrascapular. The supracleithrum is rhomboid，slightly deeper than the opercle （Fig. 3D）. The lateral line pierces the lateral portion of theposttemporal and extends posteroventrally into the dorsal portion of the supracleithrum.

The cleithrum is large and curved， with the broad orobranchial process anteriorlyoverlapped by the subopercle （Fig. 3B）. There are two postcleithra associated with thecleithrum; the dorsal is rhomboid， as deep as the supracleithrum， and the ventral is trapezoidal，nearly half the depth of the dorsal （Fig. 3）.

The pectoral fins are inserted low on the body， and each is composed of 13 distally segmentedrays. Except for the first ray， the rays are branched distally. The first ray is relatively short， precededby one or two basal fulcrum and a series of small， leaf-like fringing fulcra （Fig. 6A）. The secondray is the longest， and the remaining rays gradually reduce in length.

The pelvic girdles are not exposed. The pelvic fins are inserted at the 16th vertical scalerow， and each is composed of seven distally segmented rays. The first ray is unbranched，preceded by a basal fulcrum and a series of fringing fulcra， and the others are branched distally.

Median fins and pterygiophores The dorsal fin originates above the 23rd vertical scalerow. It is composed of 17 distally segmented rays， preceded by three basal fulcra （Fig. 6D）.Several small fringing fulcra are discernable， and they are associated with the leading marginof the first unbranched ray; the other rays are branched distally. There are 13 proximal radialsbelow the anterior 13 rays in the holotype; each supports a ray （Fig. 6D）. The posteriorproximal radials are not exposed.

The anal fin originates below the 22th or 23rd vertical scale row， composed of 12 distallysegmented rays. The first ray is unbranched， preceded by four basal fulcra and a series ofleaf-like fringing fulcra， and the remaining rays are branched distally. The rays are graduallyreduced in length posteriorly. Seven proximal radials are exposed， and each supports a ray（Fig. 6E）.

The abbreviated heterocercal caudal fin is incompletely preserved， and the total numberof rays cannot be counted （Fig. 6C）. Three procurrent and 11 principal rays can be discernablein the dorsal lobe; among these， four or five are epaxial in position. Some middle rays aremissing， and approximately ten principal rays are preserved in the ventral lobe （Fig. 6C）. Inaddition， two epaxial basal fulcra are preserved in the dorsal lobe， and some leaf-like fringingfulcra are associated with the last principal ray.

Scales The body is fully covered with rhomboid scales. The scales are arranged in 38vertical rows along the main lateral line. In the 13th vertical row of scales， there are 17–19scales on each side of the body， nine or ten below the lateral line. The lateral line scales andthose just below them in the anterior flank region are the largest， nearly twice as deep as long（Fig. 4D）. The scales gradually become shorter dorsally， ventrally and posteriorly. They have anearly smooth outer surface with a straight posterior margin. The peg-and-socket articulationbetween scales are present as commonly in other early neopterygians （Fig. 4D）.

5 Discussion

5.1 Phylogenetic analysis

Our analysis resulted in 468 most parsimonious trees （tree length = 427 steps，consistency index = 0.4496， retention index = 0.7777）， a strict consensus of which ispresented in Fig. 7. In this cladogram， three orders， Redfieldiiformes， Platysiagiformes andPolzbergiiformes， are nested successively at the basal positions of Neopterygii because theypossess the synapomorphies of the total group Neopterygii but lack two uniquely derivedfeatures of Colobodontidae and more crownward neopterygians： presence of dorsal and analfin rays that are segmented only within the distal region， and dorsal and anal fins with a 1：1ratio of fin rays to endoskeletal radials.

The family Colobodontidae was once considered synonymous with the Perleididaeamong the Perleidiformes （Stensi?， 1932）; however， later studies （Mutter， 2004; Cartanyàet al.， 2015; Xu， 2020a） revealed that both families are notably different from each other inseveral aspects： 1） a postrostral is present in the former but is lost in the latter; 2） a suborbitalis absent in the former but is present in the latter; 3） the opercle is larger than the suboperclein the former， but the latter shows a reverse condition; 4） the former has a characteristicornamentation on scales， contrasting the conditions in the latter; and 5） the former has a largernumber （56–82） of lateral line scales than does （40–50） in the latter. Furthermore， recentanalyses have shown that colobodontids lack several synapomorphies of perleidiforms sharedwith more derived neopteygians， absence of the dermosphenotic/preopercle contact （reversal inPseudobeaconia and Habroichthys）， six or fewer pairs of branchiostegal rays （reversal in somecrown neopterygians）， and 24 or fewer principal caudal rays （reversal in Fuyuanperleidus andsome louwoichthyids）. As such， the Colobodontidae is removed from the Perleidiformes and isplaced in the new order Colobodontiformes proposed herein （Table 1）.

Above the Colobodontiformes， the clade Plesiofuro–Meidiichthys， Perleidus， Teffichthysand Plesioperleidus form an unresolved polytomy within the Perleididae （Perleidiformes）. Theperleidids share four synapomorphies： 1） the preopercle/maxilla contact nearly equal to theanterior margin of subopercle in length; 2） the suborbital half as deep as the anterior marginof the preopercle; 3） the opercle no larger than subopercle in size （independently evolved inredfieldiiforms and louwoichthyiforms）; and 4） the supracleithrum deeper than the posteriormargin of the opercle. Within perleidids， Teffichthys wui sp. nov. shares two synapomorphicfeatures with T. elegans and T. madagascariensis： the presence of a suborbital and aspiracular， and a narrow contact between the preopercle and the dermopterotic. However， theinterrelationships between them are unresolved.

More crownward， Louwoichthyiformes， Luganoiiformes， Peltopleuriformes andVenusichthyidae are placed successively at the neopterygian stem （Fig. 7）. Louwoichthyiformesand Luganoiiformes are more derived than Perleidiformes because they have a veryabbreviated heterocercal caudal fin， and Peltopleuriformes and Venusichthyidae have an almosthomocercal caudal fin， resembling many crown neopterygians. In addition， venusichthyidshave a high coronoid process， a derived feature previously considered as a synapomorphy ofcrown neopterygians. Although the Venusichthyidae is sampled here by Venusichthys comptusfrom China only （Xu and Ma， 2016）， our comparative study reveals that this family is alsoknown from Europe， represented by some ‘peltopleurids’， e.g.， ‘Placopleurus’ besanenisand ‘P’. tuberculatus from the Middle Triassic of Italy and Switzerland （Brough， 1939）.Reexaminations on materials of both ‘Placopleurus’ species by the first author indicate thatthey are strikingly different from the type species of the genus Placopleurus （P. primus;Brough， 1939） but rather resemble Venusichthys comptus in many features （e.g.， opercularseries， jaws and scales）. Consequently， we would suggest the reassignment of ‘P’. besanenisand ‘P’. tuberculatus into the venusichthyid genus Venusichthys （Xu and Zhao， 2016）.

5.2 Character comparisons

The discovery of Teffichthys wui sp. nov. extends the geological range of ChineseTeffichthys from the Dienerian （Induan） of Guizhou Province （T. elegans; Yuan et al.， 2022）into the late Smithian （Olenekian） of Jiangsu and Anhui Provinces. Outside of China，Teffichthys is represented only by the type species T. madagascariensis from the earlySmithian of Madagascar （Lehman 1952; Marramà et al.， 2017）. Teffichthys wui sp. nov. differsfrom T. elegans and T. madagascariensis in having a horizontal opercle/subopercle contact，slightly fewer lateral line scales， and a slightly more anteriorly placed dorsal fin with 17 rays.Additionally， the scales of T. wui sp. nov. are smooth on the surface， and their posterior marginsare nearly straight; in other species of Teffichthys， however， the scales have some longitudinalridges on the outer surface with a serrated posterior margin （Lombardo， 2001; Xu et al.， 2015;Marramà et al.， 2017; Yuan et al.， 2022）.

Before our recovery of Teffichthys wui sp. nov.， Su （1981） and Su and Li （1983） named two perleidid taxa ‘Perleidus’ yangtzensis and Plesioperleidus dayeensis from the LowerTriassic of Anhui and Hubei Provinces， respectively. Later， Qian et al. （1997） and Liu et al.（2002） named additional perleidids， ‘Perleidus’ jiangsuensis， ‘Perleidus’ eurylepidotrichia andZhangina cylindrica from the Lower Triassic of Jiangsu Province. Jin et al. （2003） suggestedthat the latter two perleidids from Jiangsu are synonymous with ‘Perleidus’ jiangsuensis;the authors agreed on the constriction of Perleidus to include only Middle Triassic species（Lombardo， 2001） and referred ‘Perleidus’ jiangsuensis to the genus Zhangina. Tong etal. （2006） and Yuan et al. （2022）， however， considered that Zhangina is a junior synonymof Plesioperleidus according to the law of priority. Our comparative study indicates that‘Perleidus’ jiangsuensis is a junior synonym of Plesioperleidus （‘Perleidus’） yangtzensis.Teffichthys wui sp. nov. is easily distinguished from Plesioperleidus yangtzensis and otherPerleidus-like taxa in the following aspects：

（1） Relationships between dermopterotic and parietal. Teffichthys wui sp. nov. like manyother stem neopterygians have a pair of independent parietals （separated from dermopterotics）.In contrast， Plesioperleidus yangtzensis has a pair of fused parieto-dermopterotics， resemblingthe conditions of the colobodontid Feroxichthys （Xu， 2020a）， thoracopterids （Griffith， 1977;Tintori and Sassi， 1992; Xu et al.， 2012） and luganoiids （Brough， 1939; Bürgin， 1992; Xu，2020b）.

（2） Supraorbitals. Teffichthys wui sp. nov. has three supraorbitals at each side of the skull，consistent with T. elegans and Perleidus altolepis， but Plesioperleidus yangtzensis has only twosupraorbitals. Additionally， a little more supraorbitals are present in T. madagascariensis （four），Meidiichthys browni （four） and Plesiofuro mingshuica （five）， and numerous supraorbitals insome colobodontids， e.g.， nine in Feroxichthys panzhouensis and ten or more supraorbitals inCrenilepis （Mutter， 2004; Ma et al.， 2021）. Among stem neopterygians， only a few genera （e.g.，Venusichthys and Habroichthys） lack any supraorbitals （Lin et al.， 2011; Xu and Zhao， 2016）.

（3） Opercular series. Teffichthys wui sp. nov. has an opercle smaller than the subopercle，similar to the conditions in other perleidids and louwoichthyiforms （Lombardo， 2001; Xu etal.， 2015; Marramà et al.， 2017; Xu， 2021a）， and other stem neopterygians generally have anopercle larger than the subopercle. A notable difference within perleidids is that the contactsuture between opercle and subopercle is nearly straight and horizontal in Teffichthys wui sp.nov.， Perleidus altolepis and Plesiofuro mingshuica but concave and posteriorly inclined inT. elegans， T. madagascariensis and Meidiichthys browni （Hutchinson， 1973; Marramà et al.，2017）. The subopercle bears a rudimentary anterodorsal process in T. elegans and Meidiichthysbrowni， but this process is absent in Teffichthys wui sp. nov. and Perleidus altolepis（Lombardo， 2001）; additionally， the process is quite deep （44% of the depth of the opercle） incolobodontids （Ma et al.， 2021） and many holosteans （Grande and Bemis， 1998）.

（4） Lateral line scales and body shape. Teffichthys wui has 38 scales along the lateral line，slightly fewer than those in other species of this genus （40 in T. madagascariensis and 39–41in T. elegans）. In contrast， Plesioperleidus yangtzensis has 51 lateral line scales （Qian et al.，1997; Liu et al.， 2002; Jin et al.， 2003）， indicating that its body is more slender than that ofTeffichthys.

6 Conclusion

The recovery of Teffichthys wui sp. nov. documents the third and youngest species ofthe genus， providing new insights into the morphological diversity and geological range ofthe perleidids. Detailed comparisons of the new taxon with other perleidids are presented，and the diagnostic features for the genus Teffichthys and the family Perleididae are emendedaccordingly. The phylogenetic relationships of perleidiforms with other stem neopterygiansare discussed using a cladistic approach， and key characteristics of the main stem neopterygianlineages are summarized. The order Perleidiformes is restricted to include only the familyPerleididae， and the previously alleged ‘perleidiform’ family， Colobodontidae， is placed in itsown order （Colobodontiformes ord. nov.）. The revised topology and systematic classificationwould be helpful for understanding the sequence of character acquisition in the neopterygianstem.

Acknowledgements We thank Chang M.-M. and Tong J.-N. for constructive suggestions， andCavin L. and Wu F.-X. for their valuable comments on an earlier version of this manuscript.We also greatly appreciate Niu K.-C.， Richter M. and Furrer H. for granting access tocomparative fossil materials in Yingliang Stone Natural History Museum （Nan’an）， NaturalHistory Museum （London） and Pal?ontologisches Institut und Museum， Uinversit?t Zürich（Zürich）， respectively.

摘要：裂齒魚科是新鰭魚類干群的一支，只生活于三疊紀。根據(jù)江蘇句容和安徽巢湖早三疊世奧倫尼克期晚史密斯亞期海相地層中發(fā)現(xiàn)的6塊保存較好的化石，命名了裂齒魚科一新種，吳氏三疊魚（Teffichthys wui sp. nov.）。它代表了三疊魚屬的第三個種，時代上略晚于非洲馬達加斯加早史密斯亞期的馬達加斯加三疊魚和貴州印度期晚第納爾亞期的優(yōu)雅三疊魚，是該屬迄今已知最年輕的種。新種具有三疊魚屬的共近裔特征（一塊噴水骨，38–41列側(cè)線鱗，尾鰭軸上鰭條不超過3條）， 但同時它以一些自近裔特征與馬達加斯加三疊魚和優(yōu)雅三疊魚相區(qū)別，如主鰓蓋骨和下鰓蓋骨水平接觸，鱗片光滑并且后緣無鋸齒。根據(jù)新種與其他裂齒魚科魚類的詳細比較，修訂了三疊魚屬及裂齒魚科的鑒定特征。在分支系統(tǒng)學研究的基礎(chǔ)上，討論了裂齒魚科與其他新鰭魚類干群的系統(tǒng)發(fā)育關(guān)系。研究結(jié)果為了解新鰭魚類干群的系統(tǒng)發(fā)育和分類提供了新的信息。

關(guān)鍵詞：江蘇，安徽，早三疊世，裂齒魚目，骨骼學，系統(tǒng)發(fā)育

中圖法分類號：Q915.862 文獻標識碼：A 文章編號：2096–9899（2024）03–0165–21

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