Pacifiosoma cristofer ( Mikhaljova, 1993 )

Mikhaljova, Elena V., 2021, The millipede family Diplomaragnidae Attems, 1907 in the Asian part of Russia with the descriptions of two new genera and seven new species (Diplopoda, Chordeumatida), Zootaxa 5060 (1), pp. 1-44 : 28

Pacifiosoma cristofer ( Mikhaljova, 1993)

Figs 40–48

Diplomaragna cristofer Mikhaljova 1993: 18 , figs.

Diplomaragna cristofer — Mikhaljova 1997: 128, figs; 1998: 36, figs, map; Ganin 1997: 10.

Pacifiosoma cristofer — Mikhaljova 2000: 169, figs; 2004: 154, figs, map; 2009c: 4; 2017: 190, figs, map; Ganin 2009: 153; 2011: 236.

Material examined. 1 male ( FSCB), Russia, environs of Khabarovsk, near Bychikha village, Bolshekhekhtsirsky Nature Reserve , 48˚17.5´N 134˚49.7´E, 11–13.IX.2005 ; 3 males ( FSCB), Russia, environs of Khabarovsk, near Bychikha village, Bolshekhekhtsirsky Nature Reserve, 48˚14.56´N 134˚47´E, Klyuch Sosninskiy cordon, 14.IX.2005 , all leg. Yu.M. Marusik; 1 male ( FSCB), Russia, Khabarovsky Krai, Nanaisky District, Gassi Lake basin, forest along Khaso River , 31.VII.–11.VIII.2011 ; 1 male, 1 female, 1 juv. ( FSCB), Russia, Khabarovsky Krai, Nanaisky District, Gassi Lake basin, Betula with Picea forest near Tukhala River , 337.7 m, 5–9.VIII.2011 , all leg. P. V. Budilov .

Distribution. Russia: Far East (Khabarovsky Krai).

Remarks. This species was originally described in Diplomaragna from the Ulchsky District of the Khabarovsky Krai and the environs of Khabarovsk ( Mikhaljova 1993), but later transferred to the genus Pacifiosoma ( Mikhaljova 2000) . Based on type material, the gonopod structure of this species has been redescribed more adequately ( Mikhaljova 1997).

The study of the above fresh material has revealed the morphological variability of the structure of the gonopod posterior angiocoxal processes. Thus, the processes in males from the environs of Gassi Lake (pp, Fig. 41 ) are more long and slender as compared ones in males from the Bolshekhekhtsirsky Nature Reserve (pp, Fig. 42 ).

In addition, the study of the gonopods using a scanning electron microscope has allowed to clarify the detail structure of gonopods: the telopodite of the anterior gonopod is 1-segmented (joints 1 and 2 are only separated by a deep constriction, not by an intersegmental suture), subflagelliform, with a cristate apex (aat, Fig. 44 ) visible as stretched beyond sheath groove; the sheath groove longitudinally splits the distal end of posterior gonopod colpocoxite (cl, Fig. 47 ) into two tightly adjacent parts, so that the unciform apices of the colpocoxites look bifid ( Figs 46, 48 ); the colpocoxite posterior surface is finely papillate/spinulate ( Figs 42–43 ); the apex of the dentiform anterior angiocoxal processes (ap, Figs 45, 46 ) are covered with tiny tubercles ( Fig. 46 ).

It should be mentioned that Pacifiosoma acutum sp. nov. was also found near Sofiysk, Ulchsky District of the Khabarovskiy Krai, i.e. within the locality of the holotype of Pacifiosoma cristofer .

Figures

FIGURES 40–44. Pacifiosoma cristofer (Mikhaljova, 1993), males from Gassi Lake basin (Figs 40–41, 44) and Bolshekhekhtsirsky Nature Reserve (Figs 42–43). 40, 42, gonopods, caudal view, telopodites of posterior gonopods broken on fig. 42; 41, central part of gonopods; 43, distal parts of gonopods; 44, apex of colpocoxite and anterior gonopod telopodite; pp, posterior angicoxal process; aat, apex of anterior gonopod telopodite. Scales: 10 μm (Fig. 44), 20 μm (Figs 41, 43), 100 μm (Figs 40, 42).

FIGURES 45–48. Pacifiosoma cristofer (Mikhaljova, 1993), males from Gassi Lake basin (Figs 45–46) and Bolshekhekhtsirsky Nature Reserve (Figs 47–48). 45, 47, gonopods, front view; 46, 48, distal parts of colpocoxites; ap, anterior angiocoxal process; cl, colpocoxites. Scales: 20 μm (Figs 46, 48), 100 μm (Figs 45, 47).