Hastatobythites Machida, 1997

Nielsen, Jørgen G., Schwarzhans, Werner & Cohen, Daniel M., 2012, Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus, Zootaxa 3579, pp. 1-36 : 3-4

Hastatobythites Machida, 1997

Hastatobythites Machida 1997: 385 , type species by original designation Hastatobythites arafurensis Machida, 1997 . Hastatobythites: Nielsen et al. 1999: 105 .

Diagnosis. A monotypic genus of the subfamily Bythitinae ( Cohen & Nielsen 1978: 42) with the following characters: two spines placed in midline of head, one anteriorly directed on frontal above eye and another upward directed, weak and thin on ethmoid, three bony ridges on dorsum behind frontal spine; maximum width of head 5.6–6.0% SL and of body 3.5–3.9 % SL. Also the following combination of characters is diagnostic: Elongate body with joined vertical fins; head naked and anterior part of body with scattered scales in midline and posterior half of body almost fully scaled; skin thin, translucent; eye diameter less than snout-length; opercular spine covered by skin; posterior part of maxilla greatly expanded vertically; dentigerous bones with granular teeth; palatines with 2–3 tooth rows; pectoral peduncle slightly longer than broad, not adnate; gill opening extending well above opercular spine; anterior gill arch with three long rakers; precaudal vertebrae 15 and total vertebrae 57–58; fin rays in dorsal 99–100, caudal 12, anal 64–65 and pectoral 16–17; otolith length to height = 2.5, sulcus undivided, placed in central part of inner face, otolith length to sulcus length = 2.7.

Similarity. Hastatobythites is most similar to Saccogaster in having more or less prolonged pectoral radials, naked head, teeth on palatines and thin skin. Hastatobythites differs from Saccogaster by having one median spine on frontal plate (vs. a pair or none), very narrow head (5.6–6.0 % SL vs. 10.5–15.0 % SL) and body (3.5–3.9 % SL vs. 4.2–9.5 % SL) and three median bony ridges behind frontal spine (absent or one in Saccogaster ). Hastatobythites differs from Parasaccogaster n. gen. in the very narrow head, three median bony ridges behind frontal spine, prolonged free pectoral radials (vs. adnate) and the thin, tight head skin (vs. thick and loose).

Pectoral Dorsal Anal

Species 75 77 79 81 83 85 87 89 91 93 95 97 99 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65

12 13 14 15 16 17 18 19 20 21 22 23

–

74

–

76 78

–

80

–

82

–

84

– –

86

–

88

–

90 92

– –

94 96

–

98

–

100 – 36 – 38 – 40 42 – – 44 46 – 48 – 50 – – 52 54 – 56 – 58 – 60 – 62 – 64 – H. arafurensis + + + + + P. melanomycter + + +

P. normae + + + + + + + + P. rhamphidognatha + + +

S. brayi + + +

S. hawaii + + + S. horrida + + + S. maculata + + + + + + + S. nikoliviae + + + + + + + +

S. parva + + + S. staigeri + + + + + + + S. tuberculata + + + + + + + + + + + + + +