Martenseya minutocaeca, Shear, 2021

Shear, William A., 2021, Additions to the millipede family Caseyidae. II. Martenseya, a new genus of miniature, blind millipedes from California (Diplopoda, Chordeumatida Striariidea, Striarioidea, Caseyidae), Zootaxa 4984 (1), pp. 108-113 : 111

Martenseya minutocaeca new species

Figs 1−8

Type material. USA: California: Holotype male, Marin County, Phoenix Lake, 0.5 mi (0.8 km) west of Kentfield , 200’ (61m) asl, 37°57’15.84”N, 122°34’35.40”W, A.K. Johnson leg. 30.12.1977 . Paratypes: 8 male and 8 female paratypes, with same data as for holotype (all material deposited in the Florida State Collection of Arthropods , Gainesville, Florida, USA).

Diagnosis. As for the genus.

Etymology. The species epithet is an adjective, a Latin neologism combining minutus -, small, and - caecus, blind.

Description. Male (holotype). 30 rings (collum + 26 podiferous rings + 2 nonpodiferous rings + pygidium). Length 3.2 mm, width 0.4 mm. Color white, some specimens have faint, reticulate purplish brown patterning on head, collum and anterior rings. Head finely, densely setose. Ommatidia absent. Antennae ( Fig. 1 ) relatively short, clavate, antennomeres in order of length, 4>2>3=5, 6>1>7>8; fourth antennomere inflated, much the largest. Collum semilunate, narrower than head. Metazonites smooth to velutinous; outer segmental setae on laterally projecting tubercle ( Fig. 2 ), giving a serrate appearance to the trunk when seen dorsally ( Fig. 3 ), segmental setae short, clavate. Rings 28, 29 without legs. Pygidium small, rounded, spinnerets directed posteriorly. Legpairs 2−7 somewhat crassate, legpair 2 ( Fig. 4 ) with vas deferens opening through short tube on coxae, legpair 3 without coxal modifications, telopodites slightly reduced or similar in size to those of legpair 4. Gonopods ( Figs 5–6 ) compact, with large, well−sclerotized sternum anteriorly, sternum with rounded, ventrally projecting plate in midline. Coxae subglobular, setose, each bearing two narrow angiocoxites; anterior angiocoxites straight, directed somewhat anteriorly, with fine small fimbriae at tips; posterior angiocoxites curved, with distinct pseudoarticulation, directed anteriorly between anterior angiocoxites, with small teeth in distal half. Flagellocoxites and colpocoxites absent. Ninth legs ( Fig. 7 ) larger than gonpods, coxae separate from sternum, bearing flattened, twisted process distally finely toothed, medially with deep pits possibly representing gland openings. Telopodites sparsely setose, curved dorsally, very obvious in intact specimens when viewed laterally. Legpair 10 ( Fig. 8 ) with coxae enlarged, with eversible glands anteriorly.

Female. Similar to male in nonsexual characters, but considerably larger at 4.5 mm long.

Distribution. Known only from the type locality.

Notes. The specimens were taken sorting mixed deciduous and redwood leaf litter. Tiny, litter-dwelling arthropods active in winter are rarely collected so it may be expected that this species has a wider range in the San Francisco Bay area, and that congeners may exist in similar habitats north and south along the coast.

Martenseya minutocaeca n. sp. is strikingly different from other caseyid species. Its small size and metazonital tubercles carrying the lateral metazonital setae set it apart; the smallest previously known caseyids are twice as large and all previously known caseyids have cylindrical metaterga without lateral tubercles. The male third legpair lacks the characteristic ventrally extended coxae found in all other caseyids and occuring as well in the related striariids and urochordeumatids. The gonopods are unlike those of most caseyids in their simplicity and lack of flagellocoxites; these characters may be related to simplification connected to small size.

Figures

FIGURES 1−8. Martenseya minutocaeca n. sp., male (drawings not to scale). 1 Right antenna, frontal (setation omitted). 2–3 Tenth diplosegment (2 anterior, 3 dorsal [anterior side below]). 4 Right leg 2, anterior (setation omitted). 5–6 Gonopods (5 anterior, 6 posterior). 7 Ninth legpair, anterior (left telopodite omitted). 8 Tenth legpair, anterior (setation omitted). Scale line: 0.3 mm (1), 0.10 mm (4–6), 0.25 mm (2–3, 7–8).