Lophoproctus viator, Recuero & Rodríguez-Flores & Giribet, 2024

Recuero, Ernesto, Rodríguez-Flores, Paula C. & Giribet, Gonzalo, 2024, Surfing in the Eastern Atlantic: a new bristle millipede from Iberia and the Canary Islands with insights into the phylogeny of Lophoproctus (Diplopoda: Polyxenida: Lophoproctidae), Journal of Natural History 58 (9 - 12), pp. 422-439 : 427-434

Lophoproctus viator sp. n.

( Figures 3–7 )

Material examined

Type material. Holotype: female, MCZ: IZ:167469, Spain: Cuenca : Saelices, 39.8853°N, 2.7861°W, 3 December 2021, P. Rodríguez-Flores and M. García-París leg. Paratypes: 5 males, 3 females [ MCZ: IZ:161725, three of them (1 male, 2 females) mounted and preserved together on an SEM stub], same data as holotype; 1 male, 5 females ( MNCN: 20.07/2117–20.07/2122), same locality as holotype, 21 February 2021, P . Rodríguez-Flores and E . Recuero leg .; 6 males ( MNCN: 20.07/2123–20.07/2128), Spain, Cuenca, Saelices, 39.9014°N, 2.7964°W, 9 November 2012, E . Recuero and M . García-París leg.

Additional material. 1 female ( MNCN: 20.07/2135), Spain: Cuenca: Puerto de Cabrejas , 40.0719°N, 2.3108°W, 9 December 2012, E . Recuero and M . García-París leg .; 1 male ( MNCN: 20.07/2129), Spain: Cuenca: Cuenca , 40.085°N, 2.1403°W, 3 June 2018, P . Rodríguez-Flores and E . Recuero leg .; 1 male, 2 females ( MNCN: 20.07/2130), Spain: Cuenca: Villamayor de Santiago , 39.7083°N, 2.898°W, 3 March 2021, N . Cardo leg .; 1 male, 2 females ( MNCN: 20.07/2136), Spain: Albacete : 2 Km SW Munera, 39.0092°N, 2.5164°W, 22 October 2017, A . Sánchez-Vialas, R. González-Miguéns, K. López-Estrada and M. García-París leg .; 1 male, 1 female ( MNCN: 20.07/2133–20.07/2134), Spain: Valencia: El Rebollar, 39.4675°N, 1.018°W, 21 February 2021, P . Rodríguez-Flores, E . Recuero leg .; 4 males, 1 female ( MNCN: 20.07/2131–20.07/2132), Spain: Santa Cruz: El Hierro: Villa de Valverde , 27.8011°N, 17.9153°W, 14 January 2018, P . Rodríguez-Flores, E . Recuero leg.

Etymology

From the Latin viātor (traveller), in reference to its wide, disjunct distribution. The name is a masculine noun in the nominative singular.

Diagnosis

Morphologically similar to Lophoproctus lucidus ( Chalande, 1888) , particularly in the disposition of basiconic sensilla on antennomere VI ( Figures 5C , 7B , 8B ) and the ornamentation of the labrum ( Figures 4C , 7A , 8A ), it differs in the presence of two ventral, basal acute denticles in the claw of telotarsus ( Figures 6H, 6I , 7D ); also in having the two median pairs of labral linguiform processes with pointed apex ( Figures 4C , 7A ), with only the medianmost pair pointed in L. lucidus ( Figure 8A ). In life, L. lucidus shows a conspicuous, elongated red spot on both sides of the head, below the trichobothria, that is not observed or is very faint in L. viator ( Figure 2 ). Lophoproctus pagesi also has paired claw ventral processes, but they are robust while these are slender in the new species; the two species differ in the disposition of basiconic sensilla on antennomere VI ( Condé 1981). Both L. jeanneli and L. israelensis differ from the new species by having a denticle in the telotarsus claw and no ventral processes ( Condé 1981; Short 2020). Lophoproctus coecus shows a different disposition of the basiconic sensilla on antennomere VI and lacks ventral processes in the claw ( Nguyen Duy-Jacquemin 1993; Short 2015).

Description

Measurements. Body length, excluding caudal trichome pencil, 1.63–1.86 mm. Caudal trichome bundle length, 0.34–0.39 mm. Head maximum width, 0.4–0.53 mm. 13th telotarsus length, 0.13–0.14 mm.

Colour. Body white, with no obvious lateral red spots on head ( Figure 2 ).

Head. ( Figure 4 ). Ommatidia absent. Vertex with two paramedian trichome groups formed by single rows of 11–12 trichomes plus 1 trichome posteriorly, distance between each pair of rows shorter than their length. Anterior part of vertex homogeneously covered with slender, barbate trichomes. Each side of head with 3 trichobothria arranged in an isosceles triangle; the posteriormost ones thinner and more acute than the anterior one. Gnathochilarium palps with 37–41 sensilla in males, 18–20 in females. Labrum ( Figures 4C , 7A ) with 10–11 linguiform processes on each side; the two median pairs with pointed ends; external surface of labrum ornated with two transverse rows of irregularly shaped, broad ridges.

Antennae ( Figure 5 ). Eight antennomeres, relative lengths: III <I = V = VII <II <IV = VIII <VI. Antennomere VIII with 2 apical and 2 subapical striated sensory cones. Antennomere VII with 2 long basiconic papilla ( Figures 5D , 7C ), subequal in length, inserted at the same level. Antennomere VI with 4 long basiconic sensilla ( Figures 5C , 7B ), subequal in length, the first two set at the same level on the antennomere, sensilla 3rd and 4th set higher and at slightly different levels; the 4th may be set higher or lower on the antennomere than the 3rd.

Trunk. ( Figure 3 ). Collum with a subrectangular tergite showing a glabrous central part and two-thirds covered with 42–48 trichomes on each side arranged as lateral rosettes;

lateral protuberances each with an anterior row of 5 trichomes and 2 posterior trichomes. Remaining tergites with trichomes arranged in a continuous posterior row ( Figure 6A ) and lateral transversely ovoid rosettes where trichomes are aligned in three irregular rows: Lateral protuberances with rounded trichome rosettes. Caudal pencil ( Figure 6B ) with no sexual dimorphism.

Legs. ( Figure 6C–I ). Legs with 8 podomeres, except legs 1 with 6 podomeres, lacking trochanter and basitarsus, and legs 2 and 13 with 7 podomeres, lacking trochanter. Coxae with 2 ribbed oval setae, except coxae 1, 2, 12, and 13 with 1; prefemora and femora with 1 ribbed oval setae. Tarsal spine longer than claw. Claw of telotarsus with paired, blunt dorsal tubercles and paired, acute ventral denticles ( Figures 6H, 6I , 7D ); ventral profile not showing any denticle.

Remarks

The new species is morphologically similar to Lophoproctus lucidus , matching in several important characters such as the basiconic sensillar arrangement in antennomere VI or the ornamentation of the labrum. For this reason, L. viator sp. n. was initially assigned to L. lucidus by Recuero and Rodríguez-Flores (2023).

Key to species in the genus Lophoproctus

1. Claw of telotarsus with a ventral denticle ................................................................................. 2

- Claw of telotarsus without a ventral denticle .......................................................................... 3

2. Basiconic sensilla of antennomere VI arranged in diamond pattern ........ L. israelensis

- Basiconic sensilla of antennomere VI arranged by pairs in a two-step pattern ............... ..................................................................................................................................................... L. jeanneli

3. Basiconic sensilla of antennomere VI arranged in diamond pattern ....... ....... L. coecus

- Basiconic sensilla of antennomere VI not arranged in diamond pattern ..................... 4

4. Claw of telotarsus with ventral basal processes ..................................................................... 5

- Claw of telotarsus without ventral basal processes ................................................ L. lucidus

5. Hypertrophied claw processes ............................................ ............................................ L. pagesi

- Slender claw processes .............................................. .............................................. L. viator sp. n.

Figures

Figure 2. ML phylogenetic reconstruction based on the concatenated matrix including Cox1 and 28S rRNA data. Clade support is indicated on nodes (ML/MrBayes, showing only values>70/0.70). Pictures show the general habitus of Lophoproctus viator sp. n., L. lucidus and L. jeanneli. Photos: Paula C. Rodríguez-Flores.

Figure 3. Lophoproctus viator sp. n. (MCZ:IZ:161725), SEM images of general habitus in (A) dorsal view (adult female paratype); (B) ventral view (adult male paratype); (C) lateral view (adult female paratype).

Figure 4. Lophoproctus viator sp. n. (MCZ:IZ:161725), SEM images of (A) head, dorsal view (adult female paratype); (B) head, frontal view (adult male paratype);(C) labrum (adult male paratype;arrows indicate the median pairs of labral linguiform processes); (D) labrum and gnathochilarium palp lobes (adult female paratype).

Figure 5. Lophoproctus viator sp. n. (MCZ:IZ:161725), SEM images of (A) antennomere VIII (adult male paratype); (B) detail of antennomere VIII showing apical cones (adult male paratype); (C) basiconic sensilla in antennomeres VI and VII (adult female paratype); (D) detail of basiconic sensilla of antennomere VII (adult female paratype).

Figure 6. Lophoproctus viator sp. n. (MCZ:IZ:161725), SEM images of (A) posterior barbate setae on tergite of segment 6 (adult female paratype); (B) telson and caudal trichome pencil of setae (adult female paratype); (C) male external genitalia (adult male paratype); (D) midbody legs and sternites (adult male paratype); (E) anal valves (adult male paratype); (F) coxal ribbed oval seta (adult male paratype); (G) tarsal spine 6 (adult male paratype); (H) claw of telotarsus 13 in latero-ventral view (adult female paratype; arrow indicates the ventral, basal denticles); (I) claw of telotarsus 8 in lateroventral view (adult female paratype; arrow indicates the ventral, basal denticles).

Figure 7. Lophoproctus viator sp. n. Drawings of (A) labrum; (B) disposition of basiconic sensilla of antennomere VI; (C) disposition of basiconic sensilla of antennomere VII; (D) telotarsal claw.

Figure 8. Lophoproctus lucidus. SEM images of an adult male from Blanes, Girona (MNCN: 20.07/2146): (A) head in antero-ventral view, including labrum and gnathochilarium; (B) basiconic sensilla of antennomere VI; (C) midbody legs and sternites; (D) claw of telotarsus 12 in dorso-lateral view; (E) coxal ribbed oval seta.