Delarthrum, Attems, 1936

Golovatch, Sergei I., Aswathy, Mathilakath Dasan, Bhagirathan, Usha & Sudhikumar, Ambalaparambil Vasu, 2021, Review of the millipede tribe Polydrepanini, with the description of a new species from Kerala state, southern India (Diplopoda, Polydesmida, Paradoxosomatidae, Alogolykinae), Zootaxa 5068 (4), pp. 485-516 : 499

Diagnosis of Delarthrum .

Gonofemorite elongate, slender and untwisted, its apical part typically obliquely truncate ventrad or dorsad; solenophore usually complex, protecting a long, flagelliform to somewhat ribbon-shaped solenomere (sl) devoid of a basal loop/curve ( Golovatch 2014b) ( Figs 25–44 ).

Species included: Delarthrum obscurum Attems, 1936 , the type species of Delarthrum ( Figs 27–30 ), and numerous others, including the type species of the following generic categories previously synonymized under Delarthrum (see above): Armolites spiniger ( Attems, 1936) , the type species of Armolites ( Figs 31–33 ), Martensosoma unicolor ( Attems, 1936) , the type species of Martensosoma ( Figs 34–36 ) (NB: although formally synonymized with Delarthrum ( Golovatch 1992) , Martensosoma spp. still retain two gonopodal characters that make them distinct: the femorite is devoid of any evident distal outgrowth, and the solenomere is rather ribbon-shaped than filiform; thus, Martensosoma seems best to be regarded as a defined Himalayan species-group of Delarthrum ), Nepalomorpha kuznetsovi Golovatch, 1994 , the type species of Nepalomorpha ( Figs 37–39 ), Orophosoma hingstoni ( Carl, 1935) , the type species of Orophosoma ( Figs 40, 41 ), and Parorthomorpha longiseta Golovatch, 1994 , the type species of Parorthomorpha ( Figs 42–44 ). All species of Delarthrum have been listed or described in Golovatch (2014b, 2015, 2016b), while not only Martensosoma , but also the other ex-generic categories above, currently all junior synonyms, can be considered as representing species groups of Delarthrum . Considering the removal of two Dasypharkis (see below) and the addition of a new Delarthrum from Kerala, the genus Delarthrum presently counts 55 species, the taxonomically most important of which (the type species of generic categories, presently the species groups) are being briefly reassessed and illustrated above.

Figures

FIGURES 25, 26. Polydrepanum sp. 3 (= Delarthrum sp.). Entire right gonopod, lateral and mesal views, respectively. After Bano and Murthy (1997). Scale bar: 1.0 mm.

FIGURES 27–30. Delarthrum obscurum Attems, 1936. 27. Male femur 1, lateral view. 28. Entire right gonopod, lateral view. 29, 30. Distal half of right gonopod, lateral and mesal views, respectively. After Attems (1936). Abbreviations: a, mesal distofemoral process; ad, adenostyle; sl, solenomere; sph, solenophore. Drawn not to scale.

FIGURES 31–33. Delarthrum spiniger (Attems, 1936) (= Armolites spiniger (Attems, 1936)). 31. Entire left gonopod, mesal view. 32, 33. Distal half of left gonopod, ventral and dorsal views, respectively. After Golovatch (1984). Abbreviations: a, mesal distofemoral process; sl, solenomere; sph, solenophore. Scale bar: 1.0 mm.

FIGURES 34–36. Delarthrum unicolor (Attems, 1936) (= Martensosoma unicolor (Attems, 1936)). 34. Entire right gonopod, mesal view. 35, 36. Distal half of right gonopod, lateral and submesal views, respectively.After Attems (1936). Abbreviations: sl, solenomere; sph, solenophore. Drawn not to scale.

FIGURES 37–39. Delarthrum kuznetsovi (Golovatch, 1994) (= Nepalomorpha kuznetsovi Golovatch, 1994). 37. Entire left gonopod, mesal view. 38, 39. Distal half of left gonopod, dorsal and lateral views, respectively. After Golovatch (1994a). Abbreviations: sl, solenomere; sph, solenophore. Scale bar: 0.5 mm.

FIGURES 40, 41. Delarthrum hingstoni (Carl, 1935) (= Orophosoma hingstoni (Carl, 1935)). 40. Entire right gonopod, mesal view. 41. Distal half of left gonopod, lateral view. After Carl (1935). Abbreviations: a, dorsal distofemoral process; p, basal prefemoral process; sl, solenomere; sph, solenophore. Drawn not to scale.

FIGURES 42–44. Delarthrum longisetum (Golovatch, 1994) (= Parorthomorpha longiseta Golovatch, 1994). 42. Entire left gonopod, mesal view. 43, 44. Distal half of left gonopod, dorsal and lateral views, respectively. After Golovatch (1994a). Abbreviations: sl, solenomere; sph, solenophore. Scale bar: 0.2 mm.