Pinnotheridae, de Haan, 1833

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 245-246

Key to species of family Pinnotheridae

1. Ischium of third maxillipeds rudimentary or indistinguishably fused with merus; palp not more than 0.5 times as large as merus-ischium. Carapace rounded, subquadrate or broadly transverse............................................ 2

– Ischium of third maxillipeds usually distinct from merus, although smaller, sometimes imperfectly joined with it; palp of larger size, usually about as large as merus-ischium. Carapace broadly transverse........................................ 6

2. Carapace much broader than long, anterior margin nearly straight. Pereopods 2–5 diminishing in length from anterior to posterior, pereopod 5 very small............................................................... Parapinnixa affinis

– Carapace suborbicular or subquadrate, not strikingly wider than long. Pereopods 2–5 not successively diminishing in length from anterior to posterior............................................................................... 3

3. Carapace without 2 longitudinal, impressed lines leading posteriorly from middle of upper margin of orbit. Symbiotic with ascidians.......................................................................... Pinnotheres pugettensis

– Carapace with 2 longitudinal, impressed lines leading posteriorly from middle of upper margin of orbit. Usually symbiotic with pelecypods, occasionally echinoderms, rarely ascidians................................................... 4

4. Female: pereopods 3 unlike, right longer than left. Commensal in keyhole limpet, Megathura crenulata .................................................................................................... Enigmatheres canfieldi

– Female: pereopods 3 alike. Symbiotic with pelecypods, echinoderms, rarely ascidians............................... 5

5. Female: Front sharply deflexed with transverse sulcus across vertical front between orbits; hand of cheliped widening distally, bearing two rows of setae along lower margin. Male: terminal abdominal segment semi-circular, immovable finger of chela bearing large serrate lobe on upper margin. Alaska to La Jolla, California .......................... Fabia subquadrata

– Female: Front sharply deflexed but lacking transverse sulcus across vertical front between orbits; hand of cheliped not widening distally, bearing one row of setae along lower margin. Male: terminal abdominal segment widening distally with distal margin slightly deflexed, immovable finger of chela bearing 2 small teeth or lobes on upper margin. San Pedro, California to Magdalena Bay.......................................................................... Fabia concharum

6. Carapace about as wide as long, suborbicular. Pereopods 2–5 more or less subequal, pereopod 3 longest. Carapace spotted red to purple........................................................................... Opisthopus transversus

– Carapace much wider than long. Pereopod 4 longest. Carapace whitish to brown, not spotted......................... 7

7. Pereopod 4 not markedly longer than others, legs more or less subequal. Carapace hard, granulate anteriorly; lower anterolateral margin curving gradually into posterolateral margin...................................... Scleroplax granulata

– Pereopod 4 markedly longer, larger than others. Carapace usually soft, if hard, not granulate; lower anterolateral margin forming angle with posterolateral margin....................................................................... 8

8. Carapace strongly convex, hard, 1.5 times as wide as long. Often symbiotic with holothurians.......... Pinnixa barnharti

– Carapace flat or slightly convex, more than 1.5 times as wide as long. Not symbiotic with holothurians................. 9

9. Dactyl of pereopod 5 shorter than propodus............................................................... 10

– Dactyl of pereopod 5 equal to or longer than propodus....................................................... 14

10. Apex of dactyl of pereopod 5 falling short of or just reaching distal end of merus of pereopod 4 when both legs extended.. 11

– Apex of dactyl of pereopod 5 reaching beyond distal end of merus of pereopod 4 when both are extended............... 12

11. Posteroventral margin of ischium of pereopod 5 with 2–3 large tubercles; margins of pereopod 5 with long fringe of setae.......................................................................................... Pinnixa longipes

– Posteroventral margin of ischium of pereopod 5 without tubercles; pereopod 5 without long fringe of setae.. Pinnixa tubicola

12. Ventral margin of propodus of pereopod 4 with 2 ridges, ridges granulate or serrate; dactyl of pereopod 4 spinous, slightly curved................................................................................ Pinnixa tomentosa

– Ventral margin of propodus of pereopod 4 without ridges; dactyl of pereopod 4 smooth, strongly curved................ 13

13. Male: fixed finger of chela slightly deflexed relative to palm; inner margin of dactyl of chela toothless. Female: fixed finger slightly deflexed; slight gape visible between opposing margins of fingers of chela when fingers tightly closed................................................................................................... Pinnixa littoralis

– Male: fixed finger of chela straight relative to palm; inner margin of dactyl of chela with single blunt triangular tooth. Female: fixed finger nearly straight; opposing margins of fingers of chela meeting tightly, no gape................... Pinnixa faba

14. Anterolateral aspect of carapace with granulate or serrate ridge................................................ 15

– Anterolateral aspect of carapace smooth, round; without granulate or serrate ridge................................. 19

15. Fixed finger of chela angled obliquely downward relative to palm.............................................. 16

– Fixed finger of chela straight or curving upward; not deflexed................................................. 17

16. Length of propodus of pereopod 4, l.5–2 times its width...................................... Pinnixa occidentalis

– Length of propodus of pereopod 4, at least 2.5 times its width....................................... Pinnixascamit

17. Anterior face of chela entirely smooth, without granules or with line of coarse granules just above ventral margin of propodus, scattered granules over rest of propodus........................................................ Pinnixa schmitti

– Anterior face of chela with line of tubercles or granules above ventral margin, rest of palm smooth or granulate......... 18

18. Anterior face of chela with line of tubercles just above ventral margin, largely confined to region where fixed finger meets palm; rest of palm smooth................................................................... Pinnixa hiatus

– Anterior face of chela with prominent line of densely packed granules forming ridge above ventral margin, running most of length of propodus; dorsal margin of propodus granulate...................................... Pinnixa franciscana

19. Inner margin of dactyl of chela with single small triangular tooth at midpoint....................... Pinnixa weymouthi

– Inner margin of dactyl of chela toothless.................................................................. 20

20. Fingers of chela long, about twice as long as length of palm; apex of dactyl of pereopod 5 falling short of distal end of carpus of pereopod 4 when both legs extended.................................................. Pinnixa forficulimanus

– Fingers of chela short, about as long as length of palm; apex of dactyl of pereopod 5 exceeding distal end of carpus of pereopod 4 when both legs extended................................................................ Pinnixa minuscula