Oxyurichthys, Bleeker, 1857

Zarei, Fatah, Al Jufaili, Saud M., Béarez, Philippe, Ponton, Dominique, Pruvost, Patrice & Chakona, Albert, 2025, Beyond Oman’s shores: records of Oxyurichthys omanensis (Teleostei: Gobiidae) from the central and southern regions of the Western Indian Ocean, Zootaxa 5633 (3), pp. 513-527 : 522

A key to the Oxyurichthys spp. of the central and southern regions of the Western Indian Ocean:

The key is modified from Pezold & Larson (2015) to accommodate O. omanensis .

1a. D2 I,11; upper jaw teeth 2–3 rows; tongue truncate/emarginate; nape naked, no midline crest (Southwestern Indian Ocean)............................................................................................. O. keiensis

1b. D2 I,12; upper jaw teeth 1 row, occasional teeth behind; tongue margin rounded; nape naked or scaled, midline crest present 2

2a. Tentacle, pale fleshy knob/callus on posterior-dorsal eye...................................................... 3

2b. No tentacle, knob or callus on eye........................................................................ 5

3a. Fleshy knob/callus on eye; LL 60–80, modally 68; 1–3 short papillae rows on cheek below row d (Indo-west Pacific)................................................................................................. O. papuensis

3b. Membranous tentacle on eye; LL 45–63, modally 50–56; no papillae rows below row d.............................. 4

4a. TFR 15–25, usually 19; snout 22–35% HL; papillae row 2 near or to row d; ctenoid scales on trunk to below D1; pelvic fin reaches urogenital papilla, not anal-fin origin; D2 longest ray equal to head depth (Indo-west Pacific).... O. ophthalmonema

4b. TFR 23–29, usually 24–28; snout 34.9–45.4% HL; papillae row 2 significantly short of row d; ctenoid scales on trunk past third D2 element base; pelvic fin reaches or passes anal-fin origin; D2 longest ray 1.1–1.6 head depth (Western Indian Ocean)............................................................................................. O. omanensis

5a. All scales cycloid............................................................................... O. takagi

5b. Most scales ctenoid, cycloid scales limited to nape, abdomen and anterior trunk.................................... 6

6a. Distinct black spot on dorsoposterior eye; gular region dark brown or with 2 dark spots (concealed by preopercle lower edge); dark spots may be present on anal fin at base of rays (Indo-west Pacific)................................. O. lonchotus

6b. No dark spot present on dorsoposterior eye; no gular spots or dark gular region; dark spots never present at base of anal-fin rays................................................................................................ 7

7a. Pelvic fin dusky or with blackish streaks; LL 41–52 (East Africa and Madagascar).......................... O. nuchalis

7b. Pelvic fins barred or mottled and spotted; LL 61–80.......................................................... 8

8a. First five dorsal spines 16–21% SL, similar size, 4th and 5th slightly longer; pelvic fin dusky, mottled or with bars; upper jaw 61–64% HL, mean 63%; nape scaled, median naked along fleshy crest; pectoral-fin length 21–24% SL, mean 23% ( Kenya)................................................................................... O. limophilus

8b. First four dorsal spines 18–48% SL, first three averaging ~1/3 SL, fourth shorter, fifth and sixth smaller; pelvic fin with 4–5 dark bars and oval blotches crossing rays; upper jaw 52–64% HL, mean 59%; nape naked or scaled, median naked along fleshy crest; pectoral-fin length 18–29% SL, mean 23% (Indo-west Pacific)................................... O. notonema