The pineconefish, Monocentris, enters the LRT

This strangely armored marine fish
(Fig. 1) came to attention due to an earlier post on the flashlight fish, Anomalops (Fig. 2), and its seemingly unique lower eyelid filled with bioluminescence. The phylogenetic question arose: what was the situation in related taxa? How did this light organ evolve? Answer: I still haven’t found the transitional taxon.

Figure 1. Monocentris with colors added.

Figure 2. Anomalops, the flashlightfish.

The traditional phylogenetic road led to
Monocentris (Fig. 1), the pinecone (aka pineapple) fish, which nested close to, but not with the flashlight fish in the large reptile tree (LRT, 1917+ taxa), on the other side of the perch clade. So, another tradition busted.

Even so, according to Wikipedia,
“On either side of the lower jaw is a bioluminescent organ called a photophore: a pale light is produced by symbiotic bacteria within the organ, and the color of the light varies with ambient light levels—orange by day and blue-green at night.”

The lower jaw is not the lower orbit,
close and it could have migrated, but at present that’s a case of convergence.

Monocentris japonica (originally Scomber japonica Houttuyn 1782; 12-17cm) is the extant Japanese pineconefish, so named because it is covered in scutes, a deeper sort of scale with bone. This nocturnal fish lives in caves. In the LRT Monocentris nests with a less exotic Paleocene taxon, Massamorichthys (Fig. 3).

Massamorichthys wilsoni (Murray 1996; up to 20cm; Paleocene) is a small extinct transitional taxa linking to smaller taxa like Danio, then sticklebacks, pipefish, sea horses and the giant oarfish. Massamorichthys lacks the cranial crest present in basal taxa, like Scorpis, the false pompano.

References
Houttuyn M 1782. Beschryving van eenige Japanese visschen, en andere zee-schepzelen. Verh. Holl. Maatsch. Wet. Haarlem. 20(2): 311-350.

wiki/Monocentridae
wiki/Monocentris_japonica