Aphaniidae

Freyhof, Jörg & Yoğurtçuoğlu, Baran, 2020, A proposal for a new generic structure of the killifish family Aphaniidae, with the description of Aphaniops teimorii (Teleostei: Cyprinodontiformes), Zootaxa 4810 (3), pp. 421-451 : 423-424

Keys to the genera of Aphaniidae

References to bars in the keys and subsequent text correspond to the dark brown or black vertical flank bars. The silvery-white alternating bars are referred to as interspaces. Several genera are identified by male colour pattern. The key is therefore designed to permit identification of nuptial adult males larger than 30 mm SL. This does not necessarily mean that smaller and younger males cannot be identified via the same characters, but it should be noted that some character states change with age and size of individuals. See Figure 1 for a two-way demonstration of character states against genera, with simplified cladograms provided by previous studies.

1a Head canals present, anterior supraorbital canal with 2–3 pores, posterior supraorbital canal with 2 pores, preopercular-mandibular canal with 6–7 pores............................................................................. 2

1b Head canals absent, cephalic sensory pores reduced to a series of neuromasts in small depressions, not connected to canals.. 3

2a In male caudal fin hyaline or white, often with yellow margin, with three, wide, bold black bars, first bar situated on caudal-fin base, shortly behind end of hypural complex, often faded (no bars in A. furcatus ). In nuptial female no dermal sheath around anterior anal-fin rays............................................................................ Aphaniops

2b In male caudal fin pale or deep yellow or orange, clearly distinct from silvery interspaces of flank bars; caudal fin with 0–2, often faint bars, no bar behind end of hypural complex. In nuptial female dermal sheath present around first few anal-fin rays............................................................................................. Aphanius

3a Teeth conical, in three rows; caudal peduncle very narrow, its depth 2.5–3.2 times in its length; body naked....................................................................................................... Kosswigichthys

3b Teeth tricuspid, in one row; caudal peduncle deep, its depth 1.2–2.0 times in its length; body covered by scales, but reduced or absent in some species.................................................................................. 4

4a Pelvic fin always absent; male with flank bars behind head to vertical through dorsal-fin origin, no bars on caudal peduncle; nuptial colour pattern comprising a bold, black band with wide yellow margin on dorsal, caudal and anal fins.......... Tellia

4b Pelvic fin present; male with flank bars along entire flank or flank without bars; nuptial colour pattern comprising black, darkgrey or bluish dorsal and anal fins with silvery or bright blue lines or spots, or with a bold black or white marginal band.... 5

5a Colour pattern in male comprising grey, bluish or almost black body with often irregular set and shaped, iridescent blue-white to silvery spots, or spots forming narrow vertical rows on flank, especially in juveniles; male with very narrow, blue-white or silvery rows of spots or small blotches forming bands on black or blue caudal fin. Female with many silvery spots or small blotches on flank; without diamond-shaped or roundish bold black blotch at mid-height of caudal-fin base...... Paraphanius

5b Colour pattern in male comprising silvery body with very regular set and shaped, rarely irregular, brown or black bars on flank, overlaid with iridescent silvery spots in some species; male with bold, black or brown bars or with narrow brown bands on hyaline, white or yellow caudal fin, or caudal fin hyaline, with white margin in some species. Female with numerous black or brown spots, blotches or bars on flank; with a diamond-shaped or roundish bold black blotch at mid-height of caudal-fin base.................................................................................................... 6

6a Caudal fin in male without bars or rows of spots, or with 1–5 indistinct vertical rows of small brown spots on proximal portion of caudal fin in some species; dorsal-fin margin white, caudal- and anal-fin margins often white; if dorsal and anal-fin margins black ( E. isfahanensis ) caudal fin without rows of spots or bars......................................... Esmaeilius

6b Caudal fin in male with 1–4 bold black bars or numerous vertical rows of small black or brown spots (4–14 in A. villwocki , bars rarely absent in A. saourensis ); dorsal- and usually anal-fin margin black.......................................... 7

7a Dorsal fin in nuptial male completely black or with a wide greyish or black margin, a white proximal band or with a proximal row of white spots or blotches distinctly or slightly above dorsal-fin base; flank in male with 5–13 regularly shaped and set bars (13–25 in A. villwocki ); bars not overlaid with white spots (but irregular and overlaid with white spots in A. irregularis )............................................................................................... Anatolichtys

7b Dorsal fin in nuptial male with a narrow black margin and a white or hyaline submargin; flank bars in male absent ( A. saourensis ) or with 14–22 irregularly shaped and set bars; bars usually split vertically and overlaid with many minute whitish spots.......................................................................................... Apricaphanius

Remarks. The generic concept for Aphaniidae suggested here is based on the criteria monophyly, morphological diagnosability, and reasonable compactness (Gill et al. 2005; Borkenhagen 2017). The proposed genera fulfil these criteria, because all of them are monophyletic groups that can be diagnosed by a combination of morphological characters (with few complications see below), and the genera each encompass one to 13 species, which are much more closely related to each other than to the species of another genus.

The grouping of Aphaniidae into well-defined genera is based on phylogenies published by Hrbek et al. (2002) and Hrbek & Mayer (2003), who analysed the genes encoding the 12S and 16S ribosomal RNAs, several transfer RNAs, and complete NADH dehydrogenase subunits I and II. These comprehensive analyses are partly congruent with the COI-based studies by Geiger et al. (2014) and Esmaeili et al. (2020). Esmaeili et al. (2020) separated Aphaniops and Paraphanius and maintained all other species in Aphanius , but this approach fails to account for morphological characters and ignores the ambiguous phylogenetic position of Tellia (see Hrbek et al. 2002). Our concept of eight genera integrates morphological characters and the compactness of the monophyletic species groups in Aphaniidae , even if this concept is challenged by the poor diagnosability of the proposed genus Apricaphanius against Anatolichthys .

Four of the eight aphaniid genera proposed in the present study are diagnosable by anatomical characters. Aphaniops possesses head canals (vs. absent in the other genera except Aphanius ) and lacks a dermal sheath overlapping the base of the anterior anal-fin rays in the nuptial female (vs. present in other genera). Tellia does not possess head canals or a pelvic fin (vs. pelvic fin present in other genera). Kosswigichthys does not possess head canals and possesses three rows of conical teeth (vs. one row of tricuspid teeth in other genera). Aphanius possesses a pelvic fin, a dermal sheath at the anal-fin base, and head canals.

The remaining genera Anatolichthys, Apricaphanius, Esmaeilius, and Paraphanius share the combination of possessing a single row of tricuspid teeth, a pelvic fin, a dermal sheath at the anal-fin base, and not possessing head canals. To keep these groups of species in a single genus ( Anatolichthys ) would violate the criterion of monophyly.

Anatolichthys, Apricaphanius, Esmaeilius, Paraphanius can be distinguished from one another by colour pattern. This phenomenon is particularly pronounced in Paraphanius, which exhibits an unusually derived colour pattern (see discussion below). Anatolichthys, Apricaphanius, and Esmaeilius can in the main be distinguished by colour pattern, but three problematic species are discussed in detail below.

Figures

FIGURE 1. Two-way demonstration of basic cladograms of Aphaniid genera against their character states. Cladograms were simplified and drawn by adapting phylogenetic trees provided by previous studies. Black bars represent presence and white bars represent absence of the corresponding character state. Small dots within the bars stand for the presence of exceptional species to the general state.