Riotintobolus mangatsiaka, Wesener, 2020

Wesener, Thomas, 2020, Ecotone shifts in southern Madagascar: first barcoding data and six new species of the endemic millipede genus Riotintobolus (Spirobolida, Pachybolidae), ZooKeys 953, pp. 1-29 : 1

publication ID

https://dx.doi.org/10.3897/zookeys.953.53977

publication LSID

lsid:zoobank.org:pub:BA81E879-88A2-495A-92FB-98D1F2909BA7

persistent identifier

https://treatment.plazi.org/id/9B563AE0-D187-481A-893B-88DF1CE920A3

taxon LSID

lsid:zoobank.org:act:9B563AE0-D187-481A-893B-88DF1CE920A3

treatment provided by

ZooKeys by Pensoft

scientific name

Riotintobolus mangatsiaka
status

sp. nov.

Riotintobolus mangatsiaka sp. nov. Figures 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6

Material examined.

1 ♂ holotype, ZFMK MYR9801, Madagascar, PN Andohahela, Mangatsiaka, 24°58.051'S, 046°33.206'E, 90 m, spiny forest, leg. Wesener and Schütte, 23.v.2007.

Paratypes: 7 ♂, 14 ♀, ZFMK MYR938, same data as holotype.

Other material examined.

1 ♂, 1 ♀, FMMC 5413, Province Toliara; RNI d’Andohahela, parcel 2; 120 m; 24°49.0'S, 46°36.6'E; pitfalls, camp 6; leg. S. Goodman 7-15.xii.1995; 1 ♂, FMMC 5379, Province Toliara; RNI d’Andohahela, parcel 2; 120 m; 24°49.0'S, 46°36.6'E; pitfalls, camp 6; leg. S. Goodman 7-15.xii.1995;

Etymology.

Mangatsiaka, after the type locality (Fig. 2 View Figure 2 ), spiny forests next to a site called Mangatsiaka, Andohahela National Parc. Noun in apposition.

Diagnosis.

Riotintobolus mangatsiaka sp. nov. shares the absence of a projecting epiproct on the telson only with R. anomalus , R. antafoky sp. nov., R. bovinus sp. nov., R. tsimelahy sp. nov. and R. lavanono sp. nov. The posterior telopod featuring two slender, sharp projections is only shared with R. bovinus sp. nov., R. tsimelahy sp. nov. and R. lavanono sp. nov. A posterior gonopod separated into three parts is only shared with R. tsimelahy sp. nov. and R. lavanono sp. nov., whose habitus and gonopods look very similar to those of R. mangatsiaka sp. nov. Both species differ in details of the tip of the posterior gonopod and in the colour of their antennae and legs, which are red in R. mangatsiaka sp. nov. and dark grey in R. lavanono sp. nov. R. mangatsiaka sp. nov. differs from R. tsimelahy sp. nov. in the presence of just one lateral processes on the posterior gonopod. All three species differ by>11% uncorrected p-distance in the COI barcoding gene.

Description.

Measurements: male holotype with 49+0 segments, ca. 42 mm long, 4.1 mm wide. Largest females of type series with 48 to 51+0 segments, up to 52 mm long, 5.4 mm wide.

Colour (in living specimens): Body rings grey, appendages red. Head, paraprocts and posterior margins of body segments darker grey to black (Fig. 4A View Figure 4 ). Ozopore openings highlighted by black spot (Fig. 4A, B View Figure 4 ).

Head: each eye with 30-35 ommatidia in six rows. Incisura lateralis open (Fig. 4C View Figure 4 ). Labrum with standard three irregular teeth and a single row of 10-12 stout marginal setae. Clypeus with two setiferous foveolae on each side (Fig. 4D View Figure 4 ). Antennae long, protruding back to segment 5. Length of antennomeres: 1<2>3=4=5=6. Second antennomere slenderer but twice as long as first. Terminal antennomere with four large sensory cones located together inside a membranous area (Fig. 5A View Figure 5 ). Antennomere 5 with 3 rows, antennomere 6 latero-apically with a single row of sensilla basiconica (Fig. 5B-E View Figure 5 ). Antennomere 6 with an unknown type of at least three sensilla or duct openings located close to disc (Fig. 5D, E View Figure 5 ).

Gnathochilarium: lamellae linguales each with two standard setae located behind one another. Stipites each with three apical setae. Palpi of similar size (Fig. 5F View Figure 5 ). Central pads with standard two sets of sensory cones, apical area with ten cones, higher area with ~ 30 (Fig. 5G View Figure 5 ).

Mandible: Stipes without projection, well rounded (Fig. 4C View Figure 4 ). Gnathal lobe, external tooth simple, rounded; mesal tooth with three cusps (Fig. 6A View Figure 6 ). Eight pectinate lamellae. Mesal margin of pectinate area (intermediate area) with ca. four rows of small, slender spines. Molar plate with few, five, transverse furrows (Fig. 6A View Figure 6 ).

Collum: smooth, laterally not protruding as far as ring 2 (Fig. 4C View Figure 4 ).

Body rings: ozopores starting at segment 6, marked by a black spot. Located on suture between meso- and metazonite. Rings with smooth, but irregular coriaecous surface, ventrally on metazona with transverse ridges.

Telson: paraprocts elongated, with weak lips, abundant micropunctation especially towards edges (Fig. 4E View Figure 4 ). Epiproct well-rounded, covering, but not reaching above paraproct (Fig. 4E View Figure 4 ). Hypoproct inconspicuous (Fig. 4E View Figure 4 ).

Legs: leg 1 with a large cylindrical coxa, twice as long as other podomeres. Tarsus with three pairs of ventral spines and an apical spine beyond claw. Leg 2 with an elongated coxa. Tarsus with three pairs of ventral spines and a short apical spine. Midbody legs with a rectangular coxa, as long as other podomeres. Each podomere ventrally with a single or a pair of apical setae, tarsus with a single apical spine and three pairs of ventral spines. Length of midbody legs ca. 1.2 times body diameter in males.

Female sexual characters. No tarsal pads, antennae shorter than male, only protruding back to ring 2. Female vulva simple, bivalve-like (Fig. 6B View Figure 6 ). Anterior plate smaller than posterior plate, opening with one row of setae on each plate, close to operculum.

Male sexual characters: tarsal pads present from leg 3 to midbody, small, inconspicuous (Fig. 4D View Figure 4 ). Coxae 3-7 without coxal processes, but coxae 3-5 swollen (Fig. 3D View Figure 3 ).

Anterior gonopod sternite massive (Fig. 4F View Figure 4 ), elongated into a wide, well-rounded triangular lobe (Fig. 4F View Figure 4 ). Sternite in anterior view well-visible, without discernible apodemes, protruding almost as high as coxal processes. Coxite with a large, well-rounded mesal process (FIg. 4F, G). Telopodite with process arising mesally (Fig. 4G View Figure 4 ), process apically curved with a large triangular projection (Fig. 4G View Figure 4 ), tip well-rounded, slightly protruding above lateral margin of telopodite (Fig. 4F View Figure 4 ). Whole telopodite process resembling an even-sided triangle.

Posterior gonopods consisting of three parts, separated by sutures or articulations (Fig. 4H View Figure 4 ): a basal coxite with a slender coxite projection and a slightly shorter telopodite, efferent duct discharging laterally (FIg. 4H, I). Process of coxite and telopodite standing in same axis (Fig. 4H View Figure 4 ). Pair of posterior gonopods located parallel to each other, connected by a small, sclerotised and visible sternite (Fig. 4H View Figure 4 ). Basal part of coxite wide, mesally with a large triangular sclerite located on lower level than remaining part (Fig. 4H View Figure 4 ). Coxite elongated. Efferent duct running at mesal margin of coxite (FIg. 4H, I) before curving to the lateral margin at beginning of telopodite (Fig. 4I View Figure 4 ). Telopodite as wide as but much shorter than coxite, standing in same axis (FIg. 4H, I), apically membranous, with two slender apical processes both diverging (FIg. 4H, I). Mesal process membranous and wider, lateral process longer, slenderer and sclerotised, efferent duct seems to be ending at base of lateral process (FIg. 4H, I). Base of lateral process with a short, membranous-white projection (Fig. 4I View Figure 4 ).

Intraspecific variation.

The number of segments varies between 47 and 51.

Live observations.

R. mangatsiaka sp. nov. could be found in great numbers in the early morning (7-9 a.m.) on the forest floor of the spiny bush. The otherwise dry spiny bush was still quite wet because of dew. No juveniles were observed. Contrary to other Riotintobolus species, such as R. mandenensis and R. minutus , R. mangatsiaka sp. nov. did not remain stiff like a stick when disturbed, but rolled-up into a spiral (Fig. 4B View Figure 4 ), a common defence behaviour for juliform millipedes.