Stenothoe frecanda Barnard, 1962

Krapp-Schickel, Traudl, 2015, Minute but constant morphological differences within members of Stenothoidae: the Stenothoe gallensis group with four new members, keys to Stenothoe worldwide, a new species of Parametopa and Sudanea n. gen. (Crustacea: Amphipoda), Journal of Natural History 49 (37), pp. 2309-2377 : 2357-2365

Stenothoe frecanda Barnard, 1962

Stenothoe frecanda Barnard 1962: 151 , fig. 18; Barnard 1966: 31

Material examined

32 males, females, juveniles, Sanur / Bali / Indonesia, algae 3 m depth, July 1993, coll. Krapp. Together with S. crenulata Chevreux. Deposited at MVRCr .

Remarks

As far as I know, no other localities were cited until now besides the Californian coast from Monterey Bay to South California shelf, 64–92 m depth.

Distribution

California, Indonesia; 3–92 m depth.

Key to Mediterranean–Atlantic Stenothoe species with telson without spines (but there may be marginal setae)

(four Atlantic ones plus three Mediterranean endemics):

1. Gn 2 propodus in male with 1–2 U-shaped incisions in the middle of the palm; in female smooth ..................................... S. cavimana Chevreux, 1908 (2–2.2 mm)

- Gn 2 propodus palm not U-shaped incised ....................................................... 2 2. P6, 7 basis hind margins rounded ...................................................................... 3

- P6, 7 basis hind margins not regularly rounded ................................................ 4

3. Gn 1 with palmar corner of about 90°; Gn 2 palm proximally with shallow excavation; U 3 peduncle much longer and thicker than ramus ........................... ........................................................................... S. brevicornis Sars, 1883 (8 mm)

- Gn 1, 2 palmar corner clearly wider; Gn 2 palm without excavation; U 3 peduncle shorterthan ramus [with pair of setae] ...... S. monoculoides ( Montagu, 1813) (3 mm)

4. P 6 basis rectolinear like P 5, hind margin totally straight [P 7 basis hind margin proximally rounded, distally narrow and straight; T with pair of setae] .............. ........................................................................ S. pieropan Krapp-Schickel, 1996b

- P 6 basis hind margin proximally rounded, distally narrow and straight ......... 5

5. P 6 and P 7 basis hind margin proximally rounded, distally narrow and straight [eyes reduced] ....................... S. elachistoides Myers & McGrath, 1980 (1.4 mm)

- P 6 basis hind margin proximally rounded, distally narrow and straight, P 7 basis hind margin regularly rounded .......................................................................... 6

6. Telson l:w = 2, with pair of fine marginal setae on distal quarter; U 2 longer ramus clearly shorter than peduncle; P 7 basis strongly widened and posteriorly regularly rounded ......................... S. elachista Krapp-Schickel, 1976 (1–1.5 mm)

- Telson l:w <2, margin naked; U 2 longer ramus about as long as peduncle; P 7 basis weakly widened and posterior margin mostly straight ................................. ................................................ S. mandragora Krapp-Schickel 1996b (1.3–2 mm)

There are only two more species worldwide without spines on the telson, S. hansgeorgi Krapp-Schickel, 2006b from Australia and S. inermis from the Indian Ocean. All the other species have spines on the telson.

Key to Mediterranean–Atlantic Stenothoe species with submarginal spines and marginal setae on the telson

(The 24 species cited above for the Atlantic plus S. bosphorana , Mediterranean endemic)

1. Body carinate ................................................. S. richardi Chevreux, 1895 (5 mm)

- Body smooth ...................................................................................................... 2

2. Peraeopods prehensile ............................. S. symbiotica Shoemaker, 1956 (7 mm)

- Peraeopods not prehensile ................................................................................. 3

3. Eyes totally lacking ............................ S. marvela Bellan-Santini, 2005 (4 mm)

- Eyes present ....................................................................................................... 4

4. Gn 1 carpus free posterior margin parallel to anterior one .............................. 5

- Gn1 carpus posterior margin mostly hidden by merus ...................................... 6

5. A 1, 2 short, robust; P 7 merus widened but not reaching distal end of carpus ... ......................................................... S. antennulariae Della Valle, 1893 (1.5 mm)

- A 1, 2 long, slender; P 7 merus reaching distal end of carpus. ............................. ............................................................... S. bosphorana Sowinski, 1898 (3–4 mm)

6. Gn 2 propodus male, female with semicircular excavation ............................. 7

- Gn 2 propodus not as above ............................................................................. 8

7. Gn 2 propodus male, female semicircular excavation on distal half of propodus, palm smooth ................................................... S. dollfusi Chevreux, 1887 (3 mm)

- Gn 2 propodus male, female excavation in the middle or proximal part of propodus, palm distally with many teeth .... S. divae Bellan-Santini, 2005 (6 mm)

8. Gn 2 propodus female with wide, regular and very shallow excavation, palm smooth (male unknown) .................. S. menezgweni Bellan-Santini, 2005 (5 mm)

- Gn 2 not excavated ............................................................................................ 9

9. Gn 2 male, female palm straight, clear defined palmar corner ............................ ............................................................................ S. minuta Holmes, 1905 (2 mm)

- Gn 2 male, female palm corner lacking ......................................................... 10

10. Gn 2 in male like in female posterior margin of propodus regularly rounded ..... 11

- Gn 2 in male propodus not regularly rounded, but with serrations, irregular incisions, easily visible humpsor teeth) ............................................................ 12

11. Sexually dimorphic, Gn 2 male larger than in female, in both sexes propodus hind margin smooth; in male length of Cx 2 and Gn 2 propodus similar; U 3 peduncle about twice as wide, beset with long spines [common in algae] ........................... ................................................................... S. tergestina ( Nebeski, 1880) (3 mm)

- Not sexually dimorphic; Gn 2 hind margin with tiny triangular hump(s) at scarcely defined palmar corner; Cx 2 much longer than Gn 2 propodus; U 3 peduncle slender, about three times as long as wide, with short spines [living in anemones] .............................. S. n. sp. Krapp-Schickel & Vader in prep. (3 mm)

12. Gn 2 dactylus ending at palmar corner in about half length of propodus posterior margin ............................................................................................................... 13

- Gn 2 dactylus ending at proximal end of propodus posterior margin .............. 14

13. Gn 2 male (females unknown) palm very finely serrated, U 3 peduncle longer than ramus .............................................................. S. coutieri Chevreux, 1908 (6 mm)

- Gn 2 female (male unknown) palm irregularly strongly serrate; U 3 peduncle subequal to ramus .............................................. S. stephensen Reid, 1951 (2 mm)

14. Gn 2 male palm straight, on palmar corner a semicircularly rounded spinose hump; P 7 merus lengthened but not widened; U 3 peduncle shorter than ramus .......................................................... S. georgiana Bynum & Fox, 1977 (3.5 mm)

- Gn 2 not as above ........................................................................................... 15

15. Gn 2 male propodus with prominent tooth/teeth on distal end of propodus, followed by a corner ...................................................................................... 16

- Gn 2 propodus male serrated or incised, but no prominent corner ................ 21

16. Gn 2 propodus with rectangular palmar corner,palm with distally narrow U-shaped excavation, followed by prominent tooth ....................................... 17

- Gn 2 propodus without U-shaped excavation ................................................. 18

17. P 7 merus distoposterior corner strongly lengthened and widened, posterodistally reachingnearly end of carpus; Gn 1 basis with groups of short setae ................... ............................................................................ S. valida Dana, 1852 (5–8 mm)

- P 7 merus widened but not much lenthened; Gn 1 basis with few short setae ..... .............................................................................................. S. senegalensis n. sp.

- P 7 merus very narrow, not widened nor lengthened; Gn 1 basis with regular setation along whole margin ................................. S. tenella Sars, 1883 (5.5 mm)

18. Gn 2 male dactylus as long as propodus ......................................................... 19

- Gn 2 male dactylus shorter than propodus ..................................................... 20

19. Gn 2 male palmar corner totally lacking; Gn 2 male palm straight, distally with minute triangular tooth near dactylus insertion; Gn 1 merus more than twice as long as wide; U 3 peduncle elongate, about 4 times as long as wide; U 3 art 1 without spines, art 2 straight ................... S. frecanda Barnard, 1962 (3–3.6 mm)

- Gn 2 male with short palm defined by small triangular tooth; Gn 1 merus less than twice as long as wide; U 3 peduncle conical, about 2–3 times as long as wide; U 3 art 1 spinose, art 2 curved and finely sculptured ........................................... ........................................................................ S. cattai Stebbing, 1906 (3–5 mm)

20. Gn 2 male palm with scattered setae, slightly serrate; dactylus with few very short setae; P 7 merus strongly lengthened and widened, reaching end of carpus; antennae short and robust, U 3 peduncle robust and longer than rami ............... ..................................................................... S. crassicornis Walker, 1897 (2 mm)

- Gn 2 male propodus and dactylus densely beset with long setae; dactylus with long setae. P 7 merus not widened, scarcely lengthened; U 3 peduncle slender, about as long as ramus ......................................................................................... ................................................................ S. eduardi Krapp-Schickel 1976 (4 mm)

21. Gn 2 palm concave [in female palm regulularly serrate, in male 3 times U-shaped incised. P 7 merus not widened nor lengthened; U 3 peduncle much longer than ramus] ........................................................... S. megacheir ( Boeck, 1871) (8 mm)

- Gn 2 propodus straight .................................................................................... 22

22. U 3 ramus art 2 curved and sculptured, proximally thickened, distally abruptly narrowed, apical end thumb-like ......................... S. clavetta n. sp. (2.5–3.5 mm)

- U 3 ramus art 2 straight and not sculptured ................................................... 23

23. Very big eyes; A 2 peduncle art 5> art 4 [Gn 2 palm partly serrated, with several triangular elevations] ... S. macrophthalma Stephensen, 1931 (single male) (7 mm)

- Eyes not very big; A 2 peduncle art 5 not longer than art 4 ........................... 24

24. Eyes normal; A 2 peduncle art 5 = art 4; Cx 2 in male and female posteriorly excavated ............................................................... S. marina ( Bate, 1857) (4 mm)

- Eyes very small; A 2 peduncle art 5 <art 4; Cx 2 in female posterior margin convex ................................................ S. microps Sars, 1895 (only female, 8 mm)

Key to Pacific Stenothoe species

1. U 3 male ramus art 2 somewhat curved, on inner side rugose ......................... 2

- U 3 male ramus art 2 straight, not sculptured .................................................. 3

2. Gn 2 propodus male and female similar, proximally rounded and distad continuously narrowing, hind margin smooth. Telson distally rounded ........................... ......................................................... S. dentirama Hirayama & Takeuchi (2 mm)

- Gn 2 propodus male and female dissimilar: in female hind margin regularly rounded, in male totally straight or even slightly concave, distally near dactylus insertion two sharp teeth ............................. S. crenulata Chevreux, 1908 (3 mm)

3. Gn 2 male and female with clear palmar corner .............................................. 4

- Gn 2 male and female without palmar corner ................................................... 5

4. A 1 in male clearly longer A 2; Gn 1 merus reaching distal carpus; Gn 2 palm straight or convex ......................... S. garpoorea Krapp-Schickel, 2009c (2.5 mm)

- A 1 shorter A 2; Gn 1 merus not reaching distal carpus; Gn 2 palm in male concave ............................................................ S. estacola Barnard, 1962 (3 mm)

5. Gn 1 propodus rectangular, anterior and posterior margin parallel, with clear palmar corner; Gn 1 merus not reaching end of carpus; Gn 2 propodus hind margin rounded, without any tooth .............. S. haleloke Barnard, 1970 (3 mm)

-

Gn 1 propodus without strong palmar corner, carpus and merus lengthened, merus reaching end of carpus; Gn 2 propodus not smooth ............................... 6

6. Gn 2 propodus male with one acute distal tooth followed by deep incision and 1–2 blunt elevations near dactylus insertion; in female blunt elevation in the middle of palm; Cx 3 rectangular .......................... S. kaia Myers, 1985 (4.2 mm)

- Gn 2 propodus male without acute tooth; Cx 3 trapez-shaped, distad widening ... 7

7. Gn 2 in male propodus hind margin with many small ‘warts’ (sometimes also found on peduncle A 2) ................. S. verrucosa Krapp-Schickel, 2009c (3.5 mm)

- Gn 2 propodus in male on distal end of smooth and straight hind margin with one triangular elevation near dactylus insertion. S. frecanda Barnard, 1962 (3.6 mm)

Key to Stenothoe from Australia and New Zealand

1. Telson naked; Gn 2 male palm with two deep excavations .................................. ................................................. S. hansgeorgi Krapp-Schickel, 2006b (3.5–4 mm)

- Telson with spines and setae; Gn 2 never deeply excavated .............................. 2

2. U 3 ramus art 1 with three groups of spines along the margin ............................ ........................................................................ S. quabara Barnard, 1974 (3 mm)

- U 3 ramus art 1 only distal spines ..................................................................... 3

3. Gn 1 length of merus, carpus and propodus subequal. Gn 2 palm in both sexes coarsly serrated. Trapez-shaped Cx 3 on distal margin stiffened by ‘stridulation ridges’. P 7 basis posteriorly broadened and much lengthened, merus distally reaching proximal end of propodus ........... S. penelopae Krapp-Schickel, 2006b (2–3 mm)

- Gn 1 propodus always longer than carpus and merus. Gn 2 palm with or without distal tooth, but never regularly serrated. P 7 basis neither much broadened nor much lengthened, merus never reaching propodus ............................................ 4

4. Gn 2 palm distally with one (more or less) prominent tooth..........................5

- Gn 2 palm smooth ............................................................................................. 6

5. Gn 2 propodus also in adults with few short setae and small triangular hump distally ................................................. S. aucklandica Stephensen, 1927 (2.5 mm)

- Gn 2 propodus of adults with long setae, distal tooth followed by V-shaped incision ........................................................... S. miersi ( Haswell, 1879) (3.5 mm)

6. P 3–4 carpus disto–posterior margin and P 5–7 carpus disto-anterior margin with stridulating humps; merus poorly produced ....... S. moe Barnard, 1972a (3 mm)

- P 3–7 carpus smooth ......................................................................................... 7

7. U 2 rami subequal; A 1 <A 2; T ratio l: w = 9: 4. S. allinga Barnard, 1974 (4 mm)

- U 2 rami clearly unequal; A 1 subequal A 2; T ratio l: w = 9: 5 ........................ .......................................................................... S. nonedia Barnard, 1974 (3 mm)

Key to Stenothoe species from the Indian Ocean

1. Telson naked. P 3–7 naked. U 3 naked, ramus art 2 straight and smooth .......... .......................................................................... S. inermis Ledoyer, 1979 (3 mm)

- Telson, peraeopods and U 3 with spines ........................................................... 2

2. U 3 ramus art 2 slender, along the distal ¾ of inner margin fine transverse sculptures ...................................................... S. gallensis Walker, 1904 (5–6 mm)

- U 3 ramus art 2 in male medially thickened, with thick sculptures .................. 3

3. U 3 ramus art 2 in male medially widened, distad gently narrowing; U 1 without peduncular spur. Gn 2 in both sexes propodus narrow, palm somewhat convave .............................................................................. S. andamanensis n. sp. (2 mm)

- U 3 ramus art 2 in male medially abruptly narrowing, second half of article with only 1/3 of width of the first one. U 1 with peduncular spur. Gn 2 female propodus regularly rounded ................................... S. himyara n. sp. (1.5–2 mm)

Key to Stenothoe species from the Subantarctis

1. Gn 2 propodus posterior margin in both sexes beset with long dense setae, at about anterior third (female) or anterior quarter (male) an acute and clearly prominent long tooth .......................... S. sivertseni Stephensen, 1949 (2.5–3 mm)

- Gn 2 propodus sculptured, but without prominent tooth .................................. 2

2. Gn 2 palm in both sexes with defined palmar corner, remaining hind margin of propodus about same length as palm. U 3 peduncle length subequal to ramus, on peduncle one distal and one medial group of spines. Eyes normal, rounded ....... ............................................................. S. magellanica Rauschert, 1998 (2.2 mm)

- Gn 2 palm without palmar corner, dactylus subequal in length to total propodus hind margin. U 3 peduncle unusually lengthened and thickened, along the margin beset with about 7 spines. Eyes very large ................. S. adhaerens Stebbing, 1888 (4 mm)

Among the material from Senegal, I found still another species, formerly placed within the genus Stenothoe :