LESTRIGONIDAE, Zeidler, 2004

Zeidler, Wolfgang, 2004, A review of the families and genera of the hyperiidean amphipod superfamily Phronimoidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 567, pp. 1-66 : 30-32

Family LESTRIGONIDAE , new family

Diagnosis

Body length up to about 7 mm, but usually less than 5 mm. Integument generally pigmented but can be transparent. Head large, spherical to quadrate in shape. Eyes large, occupying most of head surface. Some anterior pereonites fused, usually 1–2 but sometimes up to 1–5; often more pereonites fused in female than male. Coxae fused with pereonites. Antennae 1, two­articulate in females (2–3 in Hyperioides ); multi­articulate in males with enlarged callynophore, with two­field brush of aesthestascs medially. Antennae 2 reduced to one article in females; multi­articulate in males. Mandibles with palp in males, without palp in females; molar sometimes reduced. Maxillae 1 with palp and welldeveloped outer lobe (relatively less developed in species with maxilliped with reduced inner lobe); inner lobe absent. Maxillae 2 bilobed. Maxilliped with slender, or ovate outer lobes; inner lobe well­developed, about half­length outer lobes, or rudimentary. Gnathopod 1 simple, barely chelate, subchelate, or moderately chelate. Gnathopod 2 chelate. Pereopods 3–7 simple (prehensile in Phronimopsis ). Pereopod 7 subequal in length to, or slightly shorter than, P6. Uropods with articulated endopods and exopods. Telson rounded, often small, rarely as long as half of peduncle of U3. Gills on pereonites 2–6. Oostegites on pereonites 2–5.

Six genera: Lestrigonus , Phronimopsis , Themistella , Hyperioides , Hyperietta and Hyperionyx .

Remarks

Bowman (1973) has revised all of the genera of this family, except for Phronimopsis , which is considered to be monotypic. Thus, only updated information is provided here.

Species of this family are difficult to identify with certainty without some specialist knowledge. The degree of fusion of the pereonites is a critical character used to distinguish species, and while this character is constant in adults, juveniles of some species may have more pereonites fused than in adults. Thus, it is necessary to examine characters other than the fusion of pereonites, when dealing with immature specimens (see Zeidler 1998). While Bowman’s (1973) keys work relatively well for females and most males, it is still difficult to identify species in which pereonites 1 and 2 are fused dorsally in males (i.e. the genera Lestrigonus , Hyperioides and Hyperietta ). Thus, an additional key has been constructed to aid the identification of these species, but it should be used in conjunction with Bowman’s (1973) keys and excellent illustrations.

Key to the genera of the family LESTRIGONIDAE

1. Gnathopod 2 chelate, dactylus closing against robust propodus. Pereopods 3–7 prehensile ......................................................................................... Phronimopsis Claus, 1879

­ Gnathopod 2 chelate, propodus closing against spoon­shaped carpus. Pereopods 3–7 not prehensile 2

2. Pereopod 5 longer than P6 (1.1–1.2x). Pereopods 6 & 7; dactylus with distinct upward bend midway. Pereonites 1–5 fused in both sexes ............. Themistella Bovallius, 1887

­ Pereopod 5 not longer than P6. Pereopods 6 & 7 with normal dactylus. Pereonites 1–5 rarely fused .................................................................................................................. 3

3. Pereopod 5 about 0.8x length of P6 .................................. Hyperionyx Bowman, 1973

­ Pereopod 5 subequal in length to P6 ........................................................................... 4

4. Pereopod 7 clearly shorter than P5 or P6; about 0.7x length of P6 ................................ ........................................................................................... Hyperioides Chevreux, 1900

­ Pereopod 7 slightly shorter than P6 but similar in length to P5 .................................. 5

5. First two pereonites fused in adult male & female. Maxilliped; outer lobes fused medially; inner lobe rudimentary .................................................. Hyperietta Bowman, 1973

­ First three, four or five pereonites fused in adult female; first two or four pereonites fused in adult male. Maxilliped; outer lobes separate; inner lobe usually well­developed ................................................................................. Lestrigonus Milne­Edwards, 1830

Key to male species of LESTRIGONIDAE with pereonites 1–2 fused (except Phronimopsis )

1. Eyes limited to dorsal surface of head ............. Hyperioides longipes Chevreux, 1900

­ Eyes occupying most of head surface ......................................................................... 2

2. Pereopods 5–7; carpus with at least one robust seta on anterior margin....................... 3

­ Pereopods 5–7; carpus without robust seta ................................................................... 4

3. Hyperietta parviceps , H. stephenseni and H. stebbingi ................................................. .................................................— consult Bowman (1973) to distinguish these species

4. Pereopods 3 and 4; carpus with at least two conspicuous robust setae on posterior margin 5.................................................................................................................................... 5

­ Pereopods 3 and 4; carpus with only one conspicuous robust seta on posterior margin ..................................................................................................................................... 10

5. Pereopods 5–7; propodus with recurved dentate hook overlapping dactylus ................. .......................................................................... Lestrigonus crucipes ( Bovallius, 1889)

­ Pereopods 5–7; propodus with smooth spine overlapping dactylus ............................. 6

6. Gland cone pointed ventrally .................... Lestrigonus schizogeneios ( Stebbing, 1888)

­ Gland cone rounded ventrally ....................................................................................... 7

7. Gnathopod 1; basis deeply concave distally on anterior margin .................................... ................................................................................. Hyperietta luzoni ( Stebbing, 1888)

­ Gnathopod 1; basis with at most, an even bulge on anterior margin ............................ 8

8. Pereopod 5; basis relatively broad, width about 0.8x length, overlapping anterior margin of ischium ...................................................... Hyperietta vosseleri ( Stebbing, 1904)

­ Pereopod 5; basis narrow, width about 0.5x length, not overlapping ischium.............. 9

9. Gnathopod 1; propodus with one robust seta on anterior margin ................................... ......................................................................... Lestrigonus shoemakeri Bowman, 1973

­ Gnathopod 1; propodus with two robust setae on anterior margin ................................. ........................................................................ Lestrigonus latissimus ( Bovallius, 1889)

10. Head with additional eye facets dorsally; forming small lobe over A1. Pereopod 7 much shorter than P6; dactylus long, almost half­length propodus ................................ .......................................................................... Hyperioides sibaginis ( Stebbing, 1888)

­ Head with evenly spread eye facets; evenly rounded anteriorly. Pereopod 7 subequal in length to P6; dactylus short, about 0.3x length of propodus .............................................................. Lestrigonus macrophthalmus ( Vosseler, 1901)