Redescription of the eel Ilyophis arx Robins, 1976 (Anguilliformes: Synaphobranchidae: Ilyophinae) with a description of a new species of Ilyophis, and a taxonomic synopsis of the Ilyophinae Author Tighe, Kenneth A. Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D. C., U. S. A. Author Smith, David G. Smithsonian Institution, Museum Support Center, Suitland, MD, U. S. A. Author Merrett, Nigel R. Muttlebury’s Mead, Chard Street, Thorncombe, Chard, TA 20 4 NB, U. K. Author Frable, Benjamin W. 0000-0003-4525-0671 bfrable@ucsd.edu Author Zajonz, Uwe Ichthyology Section, Department of Marine Zoology, Senckenberg Research Institute and Museum of Nature, Senckenberg Society of Nature Research, Frankfurt am Main, Germany. text Zootaxa 2024 2024-09-05 5506 1 35 57 http://dx.doi.org/10.11646/zootaxa.5506.1.2 journal article 303142 10.11646/zootaxa.5506.1.2 4c4aff0c-a28e-4bd3-a63a-e9b17afeb603 1175-5326 13746099 DC6C5929-1C30-404A-A013-7DEC2A1DBAF1

TABLE 1. Morphometric, meristic and morphological data of Ilyophis arx Robins, 1976 and Ilyophis maclainei sp. nov. For bilateral pore counts, the counts are recorded left/right.

	Ilyophis arx		Ilyophis arx	Ilyophis maclainei
	(reexamination of type series)
	Holotype	Paratypes	This study	Holotype	Paratype
Total length (mm)	439	353–401 (n=3)	215–610 (n=21)	242	263
Proportions (% TL)		Mean (range)	Mean (range)
Predorsal length	17.0	17.0 (16.0–17.7)	16.1 (14.1–18.1)	15.6	15.1
Preanal length	36.9	34.8 (32.9–37.2)	36.5 (33.4–43.1)	32.2	30.0
Head length	12.0	12.5 (12.0–13.0)	12.4 (9.9–14.2)	12.6	11.9
Trunk length	24.9	22.3 (20.9–24.2)	24.1 (20.9–28.8)	19.0	18.2
Tail length	63.1	65.2 (62.8–65.7)	63.5 (56.9–66.6)	67.8	70.0
Body depth at anus	6.4	5.2 (4.6–6.1)	6.0 (4.4–7.4)	4.1	4.8
Proportions (% HL)		Mean (range)	Mean (range)
Snout length	33.9	33.9 (30.7–35.0)	30.9 (25.3–35.7)	38.6	32.8
Eye diameter	11.0	11.7 (10.1–12.8)	11.4 (9.4–13.7)	10.8	13.7
Postorbital distance	57.9	56.8 (52.9–59.8)	57.3 (54.5–62.6)	56.8	54.0
Upper-jaw length	48.4	44.9 (42.8–47.0)	46.9 (39.9–63.2)	46.7	47.8
Interorbital width	24.8	24.8 (14.3–21.0)	22.5 (14.2–31.4)	21.6	21.0
Gill-opening (GO)	12.4	10.3 (9.1–11.6)	11.4 (8.2–16.5)	9.2	11.5
Interbranchial width	20.5	19.8 (17.2–24.9)	19.6 (13.3–27.8)	12.4	12.7
Pectoral-fin length	26.9	22.7 (19.0–22.9)	19.0 (10.3–26.6)	25.5	26.1
Meristics
SO pores	3/3	3/3	3–4	3/3	3/3
IO (including AD) pores	5/5	5/5	5	6/6	6/6
POM pores	8/8	8/8	7–10	8/8	8/8
PrePectoral LL pores	3/4	3–6	2–6	4/5	5/4
PreDorsal LL pores	9/11	9–11	8–14	7/8	10/9
PreAnus LL pores	32/36	33–38	31–37	28/30	29/31
PreAnalFin LL pores	34/38	31–37	31–39	30/32	31/33
Total LL pores	39/39	38–54	31–47	89/88	94/93
Dorsal rays	322	309–315	281–347	359	339
Anal rays	257	235–261	219–251	288	291
DR-AF origin	75	67–80	70–95	66	67
PreDorsal Vertebrae	10	11–12	10–13	10	8
PreAnus Vertebrae	37	35–38	34–40	31	31
PreAnalFin Vertebrae	39	37–40	37–42	33	34
PreCaudal Vertebrae	58	57–58	54–62	53	54
Total Vertebrae	131	131–135	128–137	132	134
Morphology
Scales	No	No	No	Yes	Yes
Number of snout plicae	4	4	4	6	6
Lower jaw plicae	4	4–5	4–6	4	4