Muellerizomus palicaudatus, 2022

Magnussen, Ilian De Francesco, Müller, Sandro P., Hammel, Jörg U., Kotthoff, Ulrich & Harms, Danilo, 2022, Diversity of schizomids (Arachnida: Schizomida) revealed by new fossil genera and species from mid-Cretaceous Burmese amber with implications for a Gondwanan origin of the Burma Terrane, Zoological Journal of the Linnean Society 196, pp. 792-844 : 832-833

† MUELLERIZOMUS PALICAUDATUS DE FRANCESCO MAGNUSSEN SP. NOV.

( FIGS 32–34 )

Zoobank registration: urn:lsid:zoobank.org:act:FAEA5DC9-66A7-4500-822C-D37A86820FB3

Type material: Holotype Holotype ( Fig. 32A–D ), adult homeomorphic ♂, collection no. GPIH04894 , ex collection Patrick Müller (no. BUB558 ).

Diagnosis

† Muellerizomus palicaudatus differs from other genera by a combination of characters: pedipalps short and delicate; flagellum spatulate and semicircular at the base but narrowed and triangular posteriorly; depression on the dorsal side of the flagellum shaped like a dumbell.

Etymology

The specific epithet is based on the Latin words pala, shovel, and cauda, tail, referring to the spatulate male flagellum. It is masculine in gender.

Description

Total length from the anterior process to the base of the flagellum 2.15 mm.

C o l o u r (i n a m b e r): O c h r e – g o l d e n; p r o s o m a, opisthosoma, flagellum and pedipalps light brown– golden; legs greenish golden, original colouring equivocal.

Prosoma ( Fig. 33A, B ): Length 0.95 mm; propeltidium length ~ 0.83 mm (owing to the anterior process being missing), width 0.25 mm. Anterior process ripped apart, no setation visible. Propeltidium setation: a single median seta followed by three pairs of setae, left one missing in second pair, only left tubercle visible in third pair. Eye spots present. Mesopeltidia width (left) 0.17 mm, right one not visible owing to an air bubble in the amber. Metapeltidium not divided, length 0.25 mm, width 0.48 mm. No sternum visible owing to air bubbles in the amber.

Chelicerae: Setation of the mesal side of chelicerae not visible, except for G6-1.

Pedipalps: Short, without armature except for a mesal spur on trochanter ( Fig. 33C, D ); trochanter setation: ventral five strong setae in bulbous tubercles, three mesal setae in tubercles; femur: longer than trochanter, setation: six dorsal, two dorsomesal, two mesal; patella: shorter than femur, setation: four mesal, four ectal, five dorsomesal, three dorsoectal, three dorsal, two ventral; tibia: shorter than patella, setation: four ventral, one ventroectal, five dorsal, four ectal, four dorsoectal, three mesal; tarsus: with asymmetrical tarsal spurs, spur length 0.02 mm, setation: three ectal, three dorsoectal, three dorsal, four dorsomesal, five mesal, four ventral; claw: long, about two-thirds as long as the length of tarsus.

Legs: Left leg I aborted at the trochanter, right leg I well preserved and complete, tarsus with six segments, leg I ~1.58 times as long as the body; anterodorsal margin of femur of leg IV produced at an angle of ~90°, femur of leg IV 3.12 times longer than deep, leg IV 1.19 times longer than the total body length; leg formula: 1423.

Opisthosoma: Length 1.2 mm, width 0.49 mm; segments X–XII not elongated, XII with a rounded posterodorsal process pointing upwards at an angle of ~45°. Abdominal tergites setation: I–VIII: Dm; IX: Dl1, Dl2; X: not visible; XI: Dl1; XII: Dm, Dl1; setation pattern: 2:2:2:2:2:2:2:2:4:?:2:4. Flagellum: dorsoventrally flattened, semicircular shape at the base that narrows down towards the posterior end into a triangular shape with a rounded tip, depression on the dorsal side of the flagellum shaped like a dumbbell ( Fig. 34A–D ), length 0.26 mm, width 0.24 mm; stalk length 0.08 mm; setation: Dm1, Dl2 paired, Dm4, Dl3 paired, Vm1, Vm2 paired, Vm3 paired, Vl1 paired, Vm5, Vl2 paired.

Further measurements: Pedipalp: trochanter 0.19 mm; femur 0.29 mm; patella 0.25 mm; tibia 0.17 mm; tarsus 0.15 mm; claw 0.10 mm; total length 1.15 mm. Leg I: trochanter 0.19 mm; femur 0.79 mm; patella 0.99 mm; tibia 0.69 mm; metatarsus 0.28 mm; tarsus (tarsus segments) 0.46 mm (0.05 mm; 0.06 mm; 0.05 mm; 0.06 mm; 0.06 mm; 0.18 mm); total length 3.40 mm. Leg II: trochanter 0.14 mm; femur 0.59 mm; patella 0.29 mm; tibia 0.31 mm; metatarsus 0.30 mm; tarsus (tarsus segments) 0.30 mm (0.09 mm; 0.10 mm; 0.11 mm); total length 1.93 mm. Leg III: trochanter 0.15 mm; femur 0.52 mm; patella 0.19 mm; tibia 0.26 mm; metatarsus 0.32 mm; tarsus (tarsus segments) 0.27 mm (0.11 mm; 0.06 mm; 0.10 mm); total length 1.71 mm. Leg IV: trochanter 0.18 mm; femur 0.78 mm; patella 0.35 mm; tibia 0.52 mm; metatarsus 0.42 mm; tarsus (tarsus segments) 0.30 mm (0.10 mm; 0.08 mm; 0.12 mm); total length 2.55 mm.

Figures

Figure 32. Specimen GPIH04894, †Muellerizomus palicaudatus sp. nov., holotype. A, specimen in dorsal view, photograph. B, same, interpretative drawing. C, specimen in ventral view, photograph. D, same, interpretative drawing. See Material and methods for explanation of abbreviations. Scale bars: 1 mm.

Figure 33. Specimen GPIH04894, †Muellerizomus palicaudatus sp. nov., holotype, details. A, prosoma in dorsal view, photograph. B, same, interpretative drawing. C, left pedipalp in ectal view, photograph. D, same, interpretative drawing. See Material and methods for explanation of abbreviations. Scale bars: 0.5 mm.

Figure 34. Specimen GPIH04894, †Muellerizomus palicaudatus sp. nov., holotype, details. A, flagellum in dorsal view, photograph. B, same, interpretative drawing. C, flagellum in ventral view, photograph. D, same, interpretative drawing. See Material and methods for explanation of abbreviations. Scale bars: 0.25 mm.