Sunday, December 31, 2023

[Ichthyology • 2023] Schindleria qizma • A New Species of Schindleria (Gobiiformes: Gobiidae) from the Red Sea (Saudi Arabia) with a specialized caudal-fin complex


Schindleria qizma
Ahnelt, Macek & Robitzch, 2023


Abstract
Species of the gobiid genus Schindleria are among the smallest and fastest reproducing vertebrates of the oceans. We describe a new species, Schindleria qizma, from the Red Sea, Saudi Arabia. It is an extreme example of progenesis, within the already paedomorphic genus, with morphological traits clearly differentiating it from its congeners. Schindleria qizma has a unique, unflexed notochord with a straight urostyle of which the tip is inserted into the hypural cartilage, rather than the typical flexed notochord with an upturned urostyle of the other species of Schindleria. Schindleria qizma belongs to the short dorsal-fin type of Schindleria. It is further characterized by an elongated but relatively deep body; a short dorsal fin originating just slightly anterior to the anal fin (predorsal-fin length 59.4% of SL vs. preanal-fin length 60.2% of SL); a head continuously increasing in depth posteriorly with a straight dorsal profile; a short snout (18.6% of head length); large eyes (34.4% of head length); a short pectoral-radial plate (6.3% of SL); 13 dorsal-fin rays; 11 anal-fin rays; 0–2 procurrent rays (where the last procurrent ray is short, if present); an anal fin with the first anal-fin ray situated opposite the second dorsal-fin ray; toothless oral jaws; females with few (10–11, total) but very large (4.6% of SL) eggs and with a conspicuous urogenital papilla characterized by a wide urogenital opening flanked by two long, bilobed projections; a dorsally pigmented swim-bladder; blackish, iridescent eyes, capped by a silvery layer with irregular rows of black dots or blotches; and no additional external pigmentation on its body, at least in preserved specimens.

Keywords: Gobiiformes, paedomorphosis, progenesis, miniaturization


Schindleria qizma, sp. nov.
  
Diagnosis: A member of the SDF group of Schindleria, which can be distinguished from all members of the LDF group by a combination of following characters: (i) the dorsal fin about the same or nearly the same length of the anal fin (vs. dorsal fin distinctly longer than anal fin), (ii) a relatively short (5.8 % of SL vs. 8.7% of SL) and deep (2.2% of SL vs. 1.5% of SL) caudal peduncle, (iii) a straight (vs. flexed) urostyle, fewer procurrent rays (0–2 vs. 5–8), and absence of teeth in both jaws (vs. both jaws with teeth).
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Etymology: The name ‘qizma’ comes from the Arabic word ‘qizm’ (مزق), which means dwarf. It is a noun in apposition and refers to the very small size of the species.


Harald Ahnelt, Oliver Macek and Vanessa Robitzch. 2023. A New Species of Schindleria (Teleostei: Gobiiformes: Gobiidae) from the Red Sea (Saudi Arabia) with a specialized caudal-fin complex. Vertebrate Zoology. 73: 313-323. DOI: 10.3897/vz.73.e97515