Prismognathus

Huang, Hao & Chen, Chang-Chin, 2012, A review of the genera Prismognathus Motschulsky and Cladophyllus Houlbert (Coleoptera: Scarabaeoidea: Lucanidae) from China, with the description of two new species, Zootaxa 3255, pp. 1-36 : 17-19

Key to the male Prismognathus and Cladophyllus from China

The males can be easily distinguished from the females by the mandible with more than one inner tooth. Prismognathus sinensis is not included in the following key, as only a single female is known.

1 Width of antennal club subequal in length or longer than antennomeres 2–6. Antennomere 10 more or less bifurcated at apex........................................................................................ 2 ( Cladophyllus )

- Width of antennal club markedly shorter than antennomeres 2–6. Antennomere 10 not bifurcated at apex ... 4 ( Prismognathus )

2 Antennomere 10 deeply bifurcate at apex. Punctures on head and pronotum fine. Mentum longer than half of submentum. Pronotum with blunt lateral angles. Flagellum of median lobe more than twice longer than aedeagus, with apex not enlarged.................................................................................... C. oberthuri Houlbert

- Antennomere 10 shallowly bifurcate at apex. Punctures on head and pronotum large. Mentum shorter than half of submentum. Pronotum with sharp lateral angles. Flagellum of median lobe less than twice longer than aedeagus, with enlarged apex.... 3

3 Width of antennal club markedly longer than antennomeres 2–6. Mandible with less than 5 inner teeth and with the subbasal tooth markedly separated. Protibia almost straight. Flagellum of median lobe longer than aedeagus, more than 1/3 times wider than median lobe in ventral view and with apex markedly enlarged............................. C. bousqueti Boucher

- Width of antennal club subequal to length of antennomeres 2–6. Mandible with at least 6 inner teeth and with the subbasal one closer to the others. Protibia slightly incurved. Flagellum of median lobe shorter than aedeagus, less than 1/3 times wider than

median lobe in ventral view and with apex weakly enlarged...................................... C. nobuhikoi Ikeda 4 Apex of the mandible neither bifurcate dorsoventrally nor with a protuberance on dorsal surface, mandible at most with a continuously serrate dorsal ridge extended to apex........................................... 5 ( P. arcuatus group)

- Apex of the mandible bifurcate dorsoventrally or with an isolated protuberance on dorsal surface...... 8 ( P. dauricus group)

5 Apex of the mandible markedly curved at apex. Flagellum of median lobe more than 1.4 times as long as aedeagus....... 6

- Apex of the mandible weakly curved at apex. Flagellum of median lobe less than 1.3 times as long as aedeagus.......... 7

6 Body surface reddish brown. All femora and tibia yellowish brown. Lateral angles of pronotum sharply protruding. Mandible with curved-off part at apex shorter. Ninth abdominal segment with ventral plate abruptly contracted and markedly narrow at base. Median lobe relatively shorter and smaller in proportion to parameres................... P. haojiani Huang & Chen

- Body surfaces black. All femora and tibia black. Lateral angles of pronotum not protruding. Mandible with curved-off part at apex longer. Ninth abdominal segment with ventral plate even in width near base. Median lobe relatively longer and larger in proportion to parameres............................................................... P. arcuatus (Houlbert)

7 Abdominal ventrites without bands of setae. Pronotum broadly rounded at anterolateral corners. Intermandibular projection protruding and not transverse. Caudal ventral plate of the basal piece of the aedeagus with a shallow central split. Flagellum of median lobe with a wide apex......................................... P. kanghianus kanghianus (Didier & Séguy)

- Abdominal ventrites each with a transversal band of setae. Pronotum more or less produced at anterolateral corners. Intermandibular projection short and transverse. Caudal ventral plate of the basal piece of the aedeagus with a deep central split. Flagellum of median lobe with a thin apex.............................................. P. sukkitorum Nagai

8 Mandible without teeth at inner margin, with apex more or less trifurcated. Intermandibular projection of the head large............................................................. P. triapicalis (Houlbert) (large and medium-sized males)

- Mandible serrate at inner margin, with apex at most bifurcated. Intermandibular projection of the head small............. 9

9 Preocular margin of the head sharply angled between the eye and the anterolateral angle of the head. Flagellum of median lobe more than 1.3 times as long as aedeagus.............................................. P. prossi Bartolozzi & Wan

- Preocular margin of the head straight or rounded between the eye and the anterolateral angle of the head. Flagellum of median lobe less than 1.2 times longer than aedeagus............................................................. 10

10 Preocular margin of the head markedly rounded or convex.................................................... 11

- Preocular margin of the head nearly straight or concave...................................................... 12

11 Preocular margin of the head more expanded laterally than the external margin of the eye. Postocular margins of the head convergent posteriorly. Median lobe relatively shorter in proportion to parameres. Caudal ventral plate of the basal piece of the aedeagus with a shallow central split. Flagellum of median lobe markedly longer than aedeagus... P. alessandrae Bartolozzi

- Preocular margin of the head less expanded laterally than the external margin of the eye. Postocular margins of the head more or less swollen. Caudal ventral plate of the basal piece of the aedeagus with a deep central split. Flagellum of median lobe not longer than aedeagus................................................................ P. shani Huang & Chen

12 Preocular margins of the head markedly convergent anteriorly................................................. 13

- Preocular margins of the head nearly parallel or divergent anteriorly........................................... 16

13 Postocular margins of the head not markedly swollen. Mandible with a single subbasal tooth. Flagellum of median lobe with a thin apex........................................................................................... 14

- Postocular margins of the head markedly swollen. Mandible with double subbasal teeth. Flagellum of median lobe with a wide apex............................................................ P. formosanus Nagel and P. p il u e n s i s Sakaino

14 Dorsal subapical tooth of the mandible well defined. Ventral caudal plate of the basal piece of the aedeagus with a markedly deeper central split.................................................................. P. shani Huang & Chen

- Dorsal subapical tooth of the mandible obsolete. Ventral caudal plate of the basal piece of the aedeagus with a shallower central split......................................................................................... 15

15 Body black. Mandible strongly curved upward in lateral view...................... P. nigricolor Boucher (small males)

- Body reddish brown. Mandible rather straight, at most slightly curved in lateral view....................................................................................... P. triapicalis (Houlbert) (medium-sized and small males)

16 Submentum, metasternum and abdominal ventrites markedly pubescent.............................. P. siniaevi Ikeda

- Submentum, metasternum and abdominal ventrites nearly glabrous............................................. 17

17 Postocular margins of the head usually swollen. Anterolateral corner of the head in an obtuse angle..................................................................................... P. formosanus Nagel and P. p il u e n s i s Sakaino

- Postocular margins of the head not swollen. Anterolateral corner of the head in acute or right angle.................... 18

18 Body length 25 mm or more........................................................................... 19

- Body length less than 25 mm ........................................................................... 22

19 Dorsal ridge of the mandible without subbasal tooth. Restricted to northeast China........................................................................................ P. dauricus (Motschulsky) (large and medium-sized males)

- Dorsal ridge of the mandible with subbasal tooth. Not present in northeast China.................................. 20

20 Mandible not markedly longer than head. Outer margin of the mandible rather straight. Flagellum of median lobe with thinner apex.................................................... P. klapperichi Bomans (large and medium-sized males)

- Mandible markedly longer than head. Outer margin of the mandible more or less sinuate. Flagellum of median lobe with wider apex............................................................................................. 21

21 Mandible with a marked gap in front of the subbasal tooth. Restricted to western Yunnan and eastern Myanmar.................................................................... P. nigricolor Boucher (large and medium-sized males)

- Mandible with a small gap in front of the subbasal tooth. Not present in Yunnan and Myanmar.................................................................................... P. davidis Deyrolle (large and medium-sized males)

22 Subbasal tooth along the dorsal ridge of the mandible usually well marked. Caudal ventral plate of the basal piece of the aedeagus with a markedly deep central split............................................... P. shani Huang & Chen

- Subbasal tooth along the dorsal ridge of the mandible absent. Caudal ventral plate of the basal piece of the aedeagus with a shallow central split.................................................................................. 23

23 Mandible with a marked gap in front of the subbasal tooth. Restricted to western Yunnan and eastern Myanmar.................................................................................... P. nigricolor Boucher (small males)

- Mandible with a small gap in front of the subbasal tooth. Not present in Yunnan and Myanmar....................... 24

24 Lateral margins of the pronotum in front of lateral angles markedly convergent anteriorly.................................................................................................... P. klapperichi Bomans (small males)

- Lateral margins of the pronotum in front of lateral angles weakly convergent anteriorly............................. 25

25 Flagellum of median lobe with relatively wider apex, and with a relatively longer thread-like part. Not present in northeast China.................................................................... P. davidis Deyrolle (small males)

- Flagellum of median lobe with relatively thinner apex, and with a relatively shorter thread-like part. Restricted to northeast China.............................................................. P. dauricus (Motschulsky) (small males)