Rachel's focal taxon

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Family Scarabaeidae (Order Coleoptera)

Subfamily Scarabaeinae

Scarabaeinae beetles are dung feeders, some of which roll balls of dung to serve as food and in which to lay eggs.

Morphotype: Scarab_Beetle14

Other Taxonomy: Possibly Tribe Coprini.

Binomial: Unknown.

Location: Maliau Basin, Camel Trophy Camp, Dinner Serving Table.

Observation: Indiv122

Notes: 5-5-5 tarsal formula. Very reduced tarsae, esp. on 1st pair of legs. No claws present on terminal tarsae. Non-metallic, smooth, striped elytra which completely cover abdomen. 5 spines on 1st femur; 3 spines on 2nd femur; 4 spines on 3rd femur. 5 underside abdominal segments. Black color. Very small horn on head.

Behavior: Shy and slow and does not attempt to fly away. Keeps antennae tucked under head. Reduced tarsae, so it bears its weight on the front femurs rather than on the front terminal tarsae. When handled, the beetle tucks its legs underneath itself in a neat fashion. Small horn present on head but does not project very far. Beetle has difficulty climbing due to lack of claws.

Morphotype: Scarab_Beetle16

Other Taxonomy: Possibly Tribe Canthonini.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center.

Observation: Indiv131

Notes: 5-5-5 tarsal formula. Reduced tarsae with 2 claws per leg. Antennae have 3-lobed ends. Non-metallic, leathery, faintly striped elytra which do not completely cover abdomen. 4 spines on 1st femur; 2 spines on 2nd femur; 2 spines on 3rd femur. 5 underside abdominal segments. Brown (almost bronze) color.

Behavior: Beetle is patient and slow but attempts to fly away frequently.

Subfamily Dynastinae

The Dynastinae comprise the beetles which are often seen to have large horns on their pronota and heads, especially in the males.

Morphotype: Scarab_Beetle2

Other Taxonomy: Unknown.

Binomial: Unknown.

Location: Lambir Hills National Park, Lambir Hills HQ Porch.

Observation: Indiv52

Notes: 5-5-5 tarsal formula. 7 antennae segments with 2-lobed ends. Non-metallic, leathery elytra which completely cover abdomen. 4 spines on 1st femur; 8 spines on 2nd femur; 8 spines on 3rd femur. 5 underside abdominal segments. Black color.

Behavior: Eager climber on hands and cloth, but is patient and does not attempt to fly away when handled. Grips tightly with claws. When irritated or handled too much, it clicks or hisses with an unknown mechanism (perhaps by moving its wings underneath the elytra)

Morphotype: Scarab_Beetle3

Other Taxonomy: Possibly Tribe Oryctini.

Binomial: Unknown.

Location: Lambir HIlls National Park, Sidewalk in front of Lambir Hills HQ.

Observation: Indiv54

Notes: 5-5-5 tarsal formula. 7 antennae segments with 2-lobed ends. Non-metallic, smooth elytra which completely cover abdomen. 4 spines on 1st femur; 8 spines on 2nd femur; 6 spines on femur. 5 underside abdominal segments. Black color.

Behavior: Found at 3:35 PM. Beetle is missing one of its second pair of legs and tends to be more aggressive as a possible result. Its elytra are both cracked longitudinally, suggesting previous trauma. It keeps its antennae tucked underneath its head when handled, making them difficult to observe. It can move its head-attached horn but does not attempt to pinch with horns.

Morphotype: Scarab_Beetle11

Other Taxonomy: Possibly Tribe Oryctini.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center, Shoe area near parking lot.

Observation: Indiv125

Notes: 5-5-5 tarsal formula. Antennae with lobed ends. Non-metallic, smooth leathery elytra which completely cover abdomen. 4 spines on 1st femur; 4 spines on 2nd femur; 3 spines on 3rd femur. 5 underside abdominal segments. Shiny black color. 6 horns: pronotum has 2 large, 1 small horns, while the head has 1 large horn with 2 small horns upon it.

Behavior: Beetle is very aggressive and does not like to be touched. Claws and spines are very sharp, and the beetle is powerfully strong. Beetle seems to position itself defensively constantly. When upright, all legs are splayed out with front legs forward or raised off the ground. When upside-down, beetle does not struggle to right itself but remains still and overturned with all legs extended. Does not attempt to fly away. Antennae are kept tucked under head and were difficult to observe. When flat object is gently used to prod between pronotum and elytra, beetle tilts back its pronotum to pinch down hard on the object.

Morphotype: Scarab_Beetle12

Other Taxonomy: Unknown.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center, Porch near dining area, Porch light.

Observation: Indiv126

Notes: 5-5-5 tarsal formula. 7 antennae segments with 2-lobed ends. Non-metallic, fuzzy elytra which completely cover abdomen. 4 spines on 1st femur; 5 spines on 2nd femur; 5 spines on 3rd femur. 5 underside abdominal segments. Black color. Elytra have a fuzzy texture to the touch.

Behavior: Beetle seems aggressive and positions itself with legs splayed out.

Morphotype: Scarab_Beetle13

Other Taxonomy: Possibly Tribe Oryctini or Tribe Dynastini.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center.

Observation: Indiv128

Notes: 5-5-5 tarsal formula. 7 antennae segments with 3-lobed ends. Non-metallic, smooth elytra which do not completely cover abdomen. 4 spines on 1st femur; 5 spines on 2nd femur; 5 spines on 3rd femur. 5 underside abdominal segments. Black color. Medium-sized horn on head. Small bump-like projection on pronotum which is not a horn.


Subfamily Rutelinae

Rutelinae are root-feeders and leaf-feeders throughout their lives.

Morphotype: Scarab_Beetle5

Other Taxonomy: Possibly Tribe Anomalini.

Binomial: Unknown.

Location: Lambir Hills National Park, Lambir Hills HQ Chalet, Mercury light trap.

Observation: Indiv96

Notes: 5-5-5 tarsal formula. 5 antennae segments with 3-lobed ends. Non-metallic, smooth, striped elytra which completely cover abdomen. 4 spines on 1st femur; 3 spines on 2nd femur; 3 spines on 3rd femur. 5 underside abdominal segments. Yellowish color.

Behavior: 2 claws are present per leg, but the beetle tends to keep its claws together, using them as one claw. Many hair-like spines are present on femurs but do not seem to be true spines.

Morphotype: Scarab_Beetle7

Other Taxonomy: Unknown.

Binomial: Unknown.

Location: Pulau Gaya, Padang Point, Pulau Gaya HQ Building.

Observation: Indiv104

Notes: 5-5-5 tarsal formula. 6 antennae segments with lobed ends. Non-metallic, leathery, striped elytra which do not completely cover abdomen. 1 spine on 1st femur; 1 spine on 2nd femur; 2 spines on 3rd femur. 6 underside abdominal segments. Brown color.

Morphotype: Scarab_Beetle8

Other Taxonomy: Possibly Tribe Rutelini.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center.

Observation: Indiv109

Notes: 5-5-5 tarsal formula. 6 antennae segments with 3-lobed ends. Non-metallic, smooth elytra which do not completely cover abdomen. 2 spines on 1st femur; 2 spines on 2nd femur; 2 spines on 3rd femur. 5 underside abdominal segments. Dark green color.


Subfamily Melolonthinae

Melolonthinae form the largest subfamily of the Scarabaeidae and are known as chafers. They feed on grass roots as larvae and are nocturnal in habits in their adult stages.

Morphotype: Scarab_Beetle6

Other Taxonomy: Possibly Tribe Melolonthini.

Binomial: Unknown.

Location: Lambir Hills National Park, Lambir Hills HQ Chalet.

Observation: Indiv99

Notes: 5-5-5 tarsal formula. 7 antennae segments with 3-lobed ends. Non-metallic, scaly elytra which do not completely cover abdomen. 3 spines on 1st femur; 3 spines on 2nd femur; 3 spines on 3rd femur. 6 underside abdominal segments. Brownish scales predominate over black-colored body. Underside features white scales over black-colored body. Headwards-pointing spine present on underside between second pair of legs.

Behavior: Slow-moving and does not attempt to fly away when handled. Leaves antennae extended and lobes separated for long periods of time, even when handled.

Morphotype: Scarab_Beetle10

Other Taxonomy: Possibly Tribe Melolonthini.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center.

Observation: Indiv118

Notes: 5-5-5 tarsal formula. 7 antennae segments with 3-lobed ends. Non-metallic, scaly, striped elytra which do not completely cover abdomen. 3 spines on 1st femur; 3 spines on 2nd femur; 3 spines on 3rd femur. 6 underside abdominal segments. Headward-pointing spine present on underside between second pair of legs, although it is rather small. White-colored scales over black body.

Behavior: Often retracts head under pronotum; scales are not present in area where head retracts.

Morphotype: Scarab_Beetle15

Other Taxonomy: Possibly Tribe Melolonthini.

Binomial: Unknown.

Location: Maliau Basin, Trail between Ginseng and Serya Camps, Underside of leaf of a shrub.

Observation: Indiv130

Notes: 5-5-5 tarsal formula. Antennae have 3-lobed ends. Non-metallic, scaly leathery elytra which do not completely cover abdomen. 3 spines on 1st femur; 3 spines on 2nd femur; 3 spines on 3rd femur. 5 underside abdominal segments. Olive-colored scales over black-colored body. Head-wards pointing spine present on underside between second pair of legs.

Behavior: Beetle missing terminal tarsae on its second right leg. When carried around in a falcon tube throughout the day (I'm sorry, beetle), the beetle expelled brownish liquid, perhaps in defense. Beetle is an eager climber but is gentle and doesn't try to fly away.

Other Scarabaeidae

Morphotype: Scarab_Beetle4

Other Taxonomy: Unknown.

Binomial: Unknown.

Location: Lambir Hills National Park, Lambir Hills HQ Canteen, Kaz's hair.

Observation: Indiv92

Notes: 5-5-5 tarsal formula. Antennae segments have 3-lobed ends. Metallic, scaly elytra which completely cover abdomen. 3 spines on 1st femur; 0 spines on 2nd femur; 0 spines on 3rd femur. 5 underside abdominal segments. Gold color.

Behavior: Active beetle and attempted to fly away several times. Found around 7:30 PM.

Morphotype: Scarab_Beetle9

Other Taxonomy: Unknown.

Binomial: Unknown.

Location: Maliau Basin, Maliau Basin Study Center.

Observation: Indiv114

Notes: 5-5-5 tarsal formula. 5 antennae segments with 3-lobed ends. Non-metallic, striped leathery elytra which do not completely cover abdomen. 4 spines on 1st femur; 5 spines on 2nd femur; 4 spines on 3rd femur. 5 underside abdominal segments which are not clearly separated. Brown color.

Family Cantharidae

Morphotype: Scarab_Beetle1

Other Taxonomy: Unknown.

Binomial: Unknown.

Location: Maliau Basin, Maliau Study Center.

Observation: Indiv53

Notes: 4-4-4 tarsal formula. 9 antennae segments with clubbed ends. Nonmetallic, leathery elytra which completely cover abdomen. No spines on any femurs. 5 underside abdominal segments. Black and orange pattern on elytra. Sharp mouthparts which appear to be used for eating wood.

'NB:' This is not a Scarabaeidae, but was chosen deliberately as a contrasting member of an outgroup in order to root the Scarabaeidae tree.

Data

24 characters were gathered as well as was possible, given the condition of each beetle specimen. Of these characters, only 21 were deemed suitable and important enough for phylogenetic analysis. The following character matrix was produced in Mesquite.


One most parsimonious rooted tree (using Beetle 1, which was not a Scarabaeidae, as a deliberate outgroup) was created using the program PHYLIP.

While this tree is very clear and easy to read, two embellishments of the tree were created to better understand the relationships among the beetles.

The first tree below features a photograph or sketch of each beetle at the tip of each branch for visual comparison. Note the strong visual similarities of Beetle6, Beetle10, and Beetle15, all members of the subfamily Melolonthinae. The members of subfamily Dynastinae also tended to cluster together near the base of the tree. This may suggest that the prominent horns which are featured in this group were either lost in subsequently derived clades or that they evolved in this group alone. While the Dynastinae do not form a distinct clade on this phylogeny, the fact that horns occur mostly only in males suggests that sexual selection is at work in this clade, making it more likely to have evolved in this group alone.

The second tree below traces one of the characters considered--number of antennae segments (which excludes the number of terminal, mobile lobed regions)--throughout the tree. It is clear that seven antennal segments is an apomorphy for the Dynastinae and the Melolonthinae, as well as Beetle4, which (as of yet) was unable to be classified into a subfamily. Five antennal segments, while spread throughout several subfamilies, appear to be a clear synapomorphy in the individuals considered. Even further derived are Beetle7, Beetle8, and Beetle16, which have the synapomorphy of six antennal segments. The distribution of the antennal characters on this tree may be misleading: I was unable to retrieve antennal segment data for 5 beetles. However, these 5 beetles tend to clade together at the base of the tree in a way that makes sense based on which subfamilies they have been placed into.

Overall, the large number of characters contributed to a very robust and well-supported tree, as shown by the creation of only one most parsimonious tree in PHYLIP. I look forward to learning more about these beetles and updating the information about them as more information becomes available to me. Obtaining more detailed information about these beetles may change the perceived accuracy of the phylogenetic tree and how proper the characters chosen were for phylogenetic analysis.

(For further in-depth examination of the phylogenetic results (including visualizations of other character tracings through the tree), please examine the character matrix and trees in the NEXUS file. Feel free to email me in order that the NEXUS file may be forwarded to you.)


Individual Determined by Date Taxon Genus Species Morphotype
Indiv104 Rachel 19 June 2010 Scarab_Beetle7
Indiv104 Rachel 19 June 2010 Scarab_Beetle7
Indiv109 Rachel 28 June 2010 Scarab_Beetle8
Indiv114 Rachel 29 June 2010 Scarab_Beetle9
Indiv118 Rod 2 July 2010 Scarab_Beetle10
Indiv122 Rachel 3 July 2010 Scarab_Beetle14
Indiv125 Rachel 2 July 2010 Scarab_Beetle11
Indiv126 Rachel 2 July 2010 Scarab_Beetle12
Indiv128 Rachel 3 July 2010 Scarab_Beetle13
Indiv130 Rod 5 July 2010 Scarab_Beetle15
Indiv131 Rod 7 July 2010 Scarab_Beetle16
Indiv52 Rachel 6 July 2010 Scarab_Beetle2
Indiv54 Rachel 8 June 2010 Scarab_Beetle3
Indiv92 Rachel 10 June 2010 Scarab_Beetle4
Indiv96 Rachel 8 June 2010 Scarab_Beetle5
Indiv99 Rod 9 June 2010 Scarab_Beetle6

References

1. Zborowsky, Paul and Ross Storey. "A Field Guide to Insects in Australia." Reed Books Australia: Port Melbourne, 1996.