Halosauridae

Bañón, Rafael, Arronte, Juan Carlos, Armesto, Ángeles, Barros-García, David & Carlos, Alejandro De, 2016, Halosaur fishes (Notacanthiformes: Halosauridae) from Atlantic Spanish waters according to integrative taxonomy, Zootaxa 4184 (3), pp. 471-490 : 486

Key to species of Family Halosauridae from the eastern Atlantic Ocean waters (adapted from Smith, 2003)

1a. Top of head scaled at least as far forward as level of nostrils; lateral-line scales slightly enlarged, one such scale for each trans- verse row of body scales................................................................................ 2

1b. Top of head naked; lateral-line scales markedly enlarged, one such scale for each two to three transverse rows of body scales.....................................................................................................5

2a. Dark colour on roof of mouth does not extend lateral to palatopterygoid arcade; dark colour on floor of mouth extends only slightly anterior to tongue, leaving anteriormost part pale; 12–20 pale pyloric caeca.................... Halosaurus ovenii

2b. Entire lining of mouth dark; pyloric caeca 4–12..............................................................3

3a. Head length about 1/4 of preanal length; 8–12 long pyloric caeca................................ Halosaurus guentheri

3b. Head length about 1/3 of preanal length; 4–9 short pyloric caeca................................................4

4a. Number of gill rakers on anterior branchial arch between 13–14, longer than opposite gill laminae.. Halosaurus johnsonianus

4b. Number of gill rakers on anterior branchial arch between 7–12, shorter than opposite gill laminae..... Halosaurus attenuatus

5a. First dorsal-fin ray as long as second and segmented; scales on opercle; sheath of lateral line darkly pigmented in adults; pylo- ric caeca pale and long............................................................. Halosauropsis macrochir

5b. First dorsal-fin ray much shorter than second and unsegmented; no scales on opercle; sheath of lateral line unpigmented; pylo- ric caeca black........................................................................................6

6a. Anal opening dark blue or black, surrounded by a white field...................................................7

6b. Anal opening white, surrounded by a dark field...............................................................8

7a. Lateral-line scales contiguous; one lateral-line scale to every two body scales, 22 or 23 before anus; preoral portion of snout very long, less than two times the total snout length.......................................... Aldrovandia rostrata

7b. Lateral-line scales not contiguous but separated by body scales; one lateral-line scale to every three body scales, 18–20 scales before the anus; preoral portion of snout shorter, 2.25–2.5 the total snout length.................... Aldrovandia gracilis

8a. Palatine tooth patches contact medially; 13–15 gill rakers on anterior arch; preoral portion of snout contained about 2 times in total snout length; dorsal origin over or very slightly behind base of pelvic fin........................ Aldrovandia affinis

8b. Palatine tooth patches separated medially; 17–23 gill rakers on anterior arch; preoral portion of snout contained about 3 times in total snout length; dorsal origin distinctly behind base of pelvic fin............................................ 9

9a. Number of lateral-line scales before anus 24–28; palatine tooth patch separated from pterygoid patch by less than half its own length; number of pectoral rays 11–14................................................... .. Aldrovandia phalacra

9b. Number of lateral-line scales before anus 16– to 23; palatine tooth patch separated from pterygoid patch by 1–4 times its own length; number of pectoral rays 8– 11...................................................... .. Aldrovandia oleosa