Microgobius

Tornabene, Luke, Van, James L. & Robertson, Ross, 2012, Microgobius urraca (Teleostei: Gobiidae), a new species of goby from the tropical eastern Pacific, Zootaxa 3447, pp. 41-55 : 52-54

Key to the Pacific species of Microgobius

The following key to the Pacific species of Microgobius is largely based on diagnostic characters described by Birdsong (1981). Additional diagnostic pigmentation characters have been included in the key and photographs of freshly collected specimens of all Pacific Microgobius are included here to assist with identification of fresh material ( Figures 4–6 ). A more comprehensive comparison of morphological features across the entire genus, summarizing data from Birdsong (1981) and data from additional material examined here (Appendix I), is given in Table 2 .

1a. Second dorsal fin elements I,15 or fewer (rarely I,16); anal fin elements I,15 or fewer (rarely I,16); scales mostly cycloid... 2

1b. Second dorsal fin elements I,16 or more (rarely I,15); anal fin elements I,16 or more (rarely I,15); scales cycloid or ctenoid. 5

2a. Second dorsal fin elements I,14 or fewer; anal fin elements I,14 or fewer.......................................... 3

2b. Second dorsal fin elements I,15 (rarely I,14 or I,16); anal fin elements I,15 (rarely I,16)..............................4

3a. No patch of ctenoid scales under pectoral fin base; all scales on body cycloid, lateral scales 67–76; epaxial myosepta not darkly pigmented; caudal fin blackish, with three blue-white stripes, an oval blackish blotch on rear of first dorsal fin.......................................................................................................... M. urraca

3b. Patch of ctenoid scales under pectoral fin base; patch of 10–22 weakly ctenoid scales sometimes present immediately below first and second dorsal fin, remaining scales cycloid, lateral scales less than 48; epaxial myosepta darkly pigmented in preserved specimens; body in life silvery brown in both sexes (pale in preservation), fins grey or silvery........... M. erectus

4a. Preopercular sensory canal with three pores; lateral scale rows less than 60; pectoral rays 22–24; a prominent crescentic to ovoid dark blotch on shoulder below anterior of dorsal fin; anterior half of second dorsal fin of females often with a blue-white diagonal streak; no distinct rows of spots on first dorsal fin; no pale or blue vertical bars on body of females... M. cyclolepis

4b. Preopercular sensory canal with two pores; lateral scale rows more than 60; pectoral rays 20–21; dark spot on body below anterior dorsal spines indistinct; both sexes with two to four rows of prominent orange spots along both dorsal fins, spots dark in preservation; female often with pale or blue vertical bars both before and after pectoral fin base in life (bars less apparent in preservation); male with front half of body and head behind eye densely spotted with orange (not apparent in preservation)................................................................................................ M. curtus

5a. Scales entirely cycloid, no ctenoid patch beneath pectoral fin; pectoral fin short, usually 18–24% of SL; both sexes with low, fleshy dorsal crest..................................................................................... 6

5b. Patch of ctenoid scales present beneath pectoral fin; remaining scales cycloid or ctenoid; pectoral fin long, usually 23–27% of SL; fleshy dorsal crest absent in males, present or absent in females.............................................. 7

6a. Dorsum with a row of four or five dashes (short, thin dark lines) along the dorsal fin base (sometimes with four or five dark saddles below them), sometimes a diffuse dark blotch on shoulder below front dorsal spines; caudal fin of both sexes with an oblique red stripe across lower half (not apparent in preservation); about four enlarged, caninoid teeth in outer row of each dentary; second dorsal fin elements usually I,16; anal fin elements usually I,16.......................... M. emblematicus

6b. Dorsum without dark dashes or saddles; males with a dark bar on shoulder bordered posteriorly with blue or yellow in life, and often with a short iridescent blue stripe below posterior half of second dorsal and two large round yellow spots above anal fin; an iridescent yellow bar with a blue anterior border on shoulder in living females; about six or seven enlarged, caninoid teeth in outer row of each dentary; second dorsal fin elements usually I,17; anal fin elements usually I,17........... M. brevispinis

7a. A dark spot (sometimes diffuse) or bar present on body below origin of first dorsal fin; second dorsal fin elements usually I,16; anal fin elements usually I,16; no elongate iridescent blue blotch on body above and before anus....................... 8

7b. No dark spot or bar on body below origin of first dorsal fin; second dorsal fin elements I,16–17; anal fin elements usually I,17; in life, both sexes with an elongate iridescent blue blotch on upper belly above and before anus, and the ventral edge of the caudal fin yellow (lost in preservation); male with anal and pelvic fins bordered in yellow in life, female with a yellow stripe along base of anal fin in life.................................................................... M. crocatus

8a. Each dentary with about 15–20 teeth in outer row; fleshy dorsal crest absent in both sexes; often with a dark vertical bar on shoulder, and sometimes one to five faint vertical bars on trunk behind shoulder bar in preservation (due to the poor quality of our photos, life color patterns cannot be accurately defined)........................................ M. miraflorensis

8b. Each dentary with about seven to nine teeth in outer row; fleshy dorsal crest well developed in females; both sexes with a diffuse dark spot on body below origin of first dorsal fin; in life, both sexes with a series of four or five large iridescent blue spots along mid flank, another series of two or three iridescent blue spots along side of belly beneath pectoral fin (spots lost in preservation).................................................................................. M. tabogensis

Figures

FIGURE 4. Photographs of freshly collected M. brevispinis, M. curtus, and M. crocatus. Photos by JVT, editing by DRR.

FIGURE 5. Photographs of freshly collected M. erectus, M. emblematicus, and M. miraflorensis. Photos by JVT and Gerry Allen, editing by DRR.

FIGURE 6. Photographs of freshly collected M. cyclolepis and M. tabogensis. Photographs of males not available. Photos by Gerry Allen and JVT, editing by DRR.