Pacifiosoma triangulatum, Mikhaljova, 2021

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 : 32-33

Pacifiosoma triangulatum sp. nov.

Figs 56–57

Material examined. Holotype: male ( FSCB: 2 permanent micropreparations, N 351–352: antenna, leg pairs 1 and 7, gnathochilarium, gonopods; the head and trunk lost; a draft of a description), Pimorsky Krai , Dalnegorsky District, Picea forest, IX.1972, leg. A.N. Kupyanskaya; paratype: 1 male ( FSCB: 1 constant micropreparation, N 353: gonopod; the head and trunk lost), same locality as in holotype, IX.1972, leg. A.N. Kupyanskaya.

Diagnosis. Differs from its congeners mainly by the clawlike process of the posterior gonopod posterior angiocoxal process, as well as in the plate-like mesal margin of the colpocoxite and the flagelliform anterior angiocoxal process.

This species seems to be closely related to P. koiensis but differs in the configuration of the posterior gonopod posterior angiocoxal process supplied with a strong clawlike outgrowth (c, Fig. 56 ) (vs without clawlike outgrowth in P. koiensis ) as well as in the more slender distal part of the colpocoxite. In addition, the gonopod posterior angiocoxal processes of the new species are similar to those of P. acutum sp. nov.

Description. Male. Length 10–11 mm, width about 1.1 mm with paraterga. Coloration in alcohol beige. Legs brownish, their distal parts brown. Antennae brown. Eyes black.

Number of body rings unknown, most likely, body with 32 rings. Head densely setose. Eye patches triangular, each composed of about 30 ocelli. Antennae slender. Paraterga relatively well-developed from ring 2, on rings 5–27 their caudolateral corners beak-shaped pointed. Metazonital macrochaetae in a transverse row on somites 28–30, like an extended triangle on preceding rings. Anterolateral macrochaetae shortest. All macrochaetae pointed, but not very sharply so.

Legs long and slender. Leg pairs 1 and 2 typically reduced in size, with usual tarsal brushes. Claw of the leg pairs 1 and 2 at base with a long setoid outgrowth ventrally and two small additional claws dorsally. Other pregonopodal legs somewhat enlarged. Leg pair 7 with a group of funnel–shaped tarsal papillae apically near claw. Claws 7 at base with a long setoid outgrowth ventrally but without additional claws. Information on tarsal papillae and the claw structure of other legs absent. Legs 10 and 11 normal, with coxal glands.

Gonopods as in figs 56–57. Flagelliform anterior gonopod telopodites pass inside a short sheath groove with elevated edges. Apices of the anterior gonopod telopodites unmodified. Posterior gonopod colpocoxites fused basally, their distal parts slightly curved caudally. Each colpocoxite entire, almost completely covered with dense papillae. Mesal edge of gonopod colpocoxite drawn into a triangular plate (n, Fig. 56 ). Colpocoxite sheath groove without evident processes. Posterior gonopod angiocoxites with moderately developed elongated subglobules in posterior view, depressed centrally in anterior view. Posterior angiocoxal process (pp, Fig. 56 ) large, with wide rounded apex covered with papillae and clawlike outgrowth (с, Fig. 56 ). Anterior angiocoxal process (ap, Fig. 57 ) long, flagelliform, its distal portion placed inside frontal fold of colpocoxite. Posterior gonopod telopodite 2- segmented, setose; distal segment large.

Female unknown.

Etymology. The specific epithet refers to the triangular mesal edge of the gonopod colpocoxite, an adjective in apposition.

Figures

FIGURES 56–57. Pacifiosoma triangulatum sp. nov., male holotype. 56, gonopods, caudal view; 57, gonopods, front view; pp, posterior angicoxal process; c, clawlike outgrowth; n, triangular plate; ap, anterior angiocoxal process; cx, coxosternum. Scale in mm.