Zoosphaerium platylabum (de Saussure & Zehntner, 1902)

Wesener, Thomas & Sagorny, Christina, 2021, Seven new giant pill-millipede species and numerous new records of the genus Zoosphaerium from Madagascar (Diplopoda, Sphaerotheriida, Arthrosphaeridae), European Journal of Taxonomy 758 (1), pp. 1-48 : 24-25

Zoosphaerium platylabum species-group

Remarks

Species can be identified as members of the Zoosphaerium platylabum species-group based on the number of locking carinae (always 2) of the anal shield that are located close to the last pleurite, as well as on morphological characters of the female vulva, whose apical processes are usually sharpedged (with the exception of those in Z. tsingy Wesener, 2009 ). The posterior telopods ( Wesener & Wägele 2008) show two vastly different modifications: the movable finger is either very thick, or quite elongated and slender. The species-group now contains 6 +3 described species distributed in humid as well as western dry forests all over Madagascar. Species of this group are conspicuously absent from the southern spiny forest ecosystem (Wesener 2009).

Key to species of the Zoosphaerium platylabum species-group

1. Movable finger of posterior telopods very thick, <2 times as long as wide, width strongly decreasing towards tip; apically with minute sclerotized nubs on posterior as well as on anterior side.....................................................................................................................................................2

– Movable finger slender, at least 3 times as long as wide, width not decreasing towards tip; apically sclerotized structures only present on posterior side..........................................................3

2. Movable finger 1.2 times as long as wide, at inner margin with a small membranous lobe. First stigmatic plate greatly enlarged, lobe not triangular or tapering towards tip. Antenna with more than 35 apical cones ................................................... Z. platylabum (de Saussure & Zehntner, 1902)

– Movable finger 1.6 times as long as wide, at inner margin without lobe. First stigmatic plate large, lobe triangular and tapering towards well-rounded tip. Antenna with 23–35 apical cones .. .................................................................................................. Z. pseudoplatylabum Wesener, 2009

3. Anterior edges of thoracic shield slightly projecting towards head. Movable finger shorter than fixed finger ........................................................................................... Z. solitarium Wesener, 2009

– Anterior edges of thoracic shield well-rounded. Movable finger at least slightly longer than fixed finger..................................................................................................................................................4

4. Male harp with two stridulation ribs. Movable finger 3 times as long as wide.....................5

– Male harp with a single stridulation rib. Movable finger>4 times as long as wide................7

5. Movable finger on posterior telopods with five spines and no membranous lobes. Immovable finger of posterior telopod slender, 4 times as long as wide, apical part tapering and curved towards movable finger. Only 7 or 8 ventral spines on legs. Found in eastern rainforests, Masoala Peninsula .............................................................................................................................. Z. masoala sp. nov.

– Movable finger on posterior telopods with spines and at least one large, triangular membranous lobe. Immovable finger of posterior telopod wide, 2.7 times as long as wide, not curved, parallel to movable finger, apically only weakly tapering. 10 or more ventral spines on legs. Found in western dry forests..........................................................................................................................................6

6. Light brown. Antennae with four apical cones. Third podomere of anterior telopods lacking crenulated teeth ..................................................................................................... Z. beanka sp. nov.

– Olive green. Antennae with>15 apical cones. Third podomere of anterior telopods laterally with 2 or 3 crenulated teeth ...................................................................... Z. tsingy Wesener, 2009

7. Tergites shiny black, appendages red. Anal shield strongly developed, shaped like a helmet. Fixed finger of posterior telopod slightly curved towards movable finger. Operculum of vulva deeply notched, divided into two sharp ‘hornsʼ. Female washboard on each side with a single stridulation rib .................................................................................... Z. corystoides Wesener, 2009

– Tergites light brown or olive-brownish, appendages brown or green. Anal shield well-rounded. Fixed finger of posterior telopod parallel to movable finger.........................................................8

8. Up to 30 mm long. Movable finger of posterior telopod with 25 teeth, three spines located at apex. Endotergum with two dense rows of long marginal bristles, protruding above tergite margin. (Female unknown) ............................................................................... Z. voahangy sp. nov.

– Up to 55 mm long. Movable finger of posterior telopod with ca 15 teeth, three spines located at regular intervals along entire margin. Endotergum with a single row of short, dense marginal bristles, protruding up to ⅔ of distance towards tergite margin. Operculum of vulva only very shallowly notched, forming two sharp horns. Female washboard with four stridulation ribs ............. ............................................................................................................ Z. broelemanni Wesener, 2009